Gunbreaker Tank Advanced Optimization Guide — Dawntrail 7.0

Before talking about 2.50 GCD Gunbreaker, a disclaimer must be made. 2.50 Gunbreaker is extremely restrictive and strict. A single mistake can cost significant amounts of potency. This is not a prog friendly speed, nor is this speed recommended for someone who is just learning Gunbreaker for the first time. If this is not a concern for you, then keep reading to learn about the 2.50 rotation. If, however, this is a concern for you, the 2.40-2.47 rotation is much more forgiving and prog friendly.

Next, credit for this information must be given to Krom, Azazel, Aletin, Kyo, and the rest of The Balance's Gunbreaker team for theorycrafting and fact checking this information.

With those out of the way, lets jump into the 2.50 rotation. The following sections assume that the reader has read and understands how the basic GNB rotation works, and therefore will not be going over the basics of the rotation. Please refer back to the standard Gunbreaker Rotation Guide if you are not familiar with the basics.

Due to the fact that 2.50 can only fit eight GCDs inside of No Mercy, there is no room for error whatsoever when fitting GCDs inside the buff when Bloodfest is available. The Gnashing Fang combo, Lion Heart combo, Double Down, and Sonic Break add up to a total of eight GCDs. The Keen Brutal No Mercy opener fits these skills inside of No Mercy, while also aligning with standardized raid buff timings as much as possible for maximum potency in party buffs. An additional benefit to this opener is that it forces a "0/2 (Zero-Two) Loop", providing a bit of extra potency by allowing for Hypervelocity to be inside the No Mercy buff three out of every four windows. This loop will be explained in detail in a later section.

After the opener and between No Mercy windows, continue the rotation with the following filler priorities:

1. Use Gnashing Fang combo and Blasting Zone as soon as they are ready. Ensure you have a Cartridge to use Gnashing Fang immediately!
2. Use Burst Strike to avoid overcapping Cartridges.
3. Use the Solid Barrel combo to generate Cartridges.

No Mercy should be used as soon as it is ready, and this should result in it being early-weaved every time it is ready.

During odd minute No Mercy windows, use the follow priorities under the buff:

1. Use Double Down, Gnashing Fang, Blasting Zone, and Bow Shock as soon as they are ready.
2. If this was a Two Cartridge No Mercy window, the first GCD after No Mercy is pressed must be Solid Barrel to prevent delaying either Double Down or Gnashing Fang.
3. Use Sonic Break as the first GCD after No Mercy, unless it is a Two Cartridge No Mercy window. Use it after Gnashing Fang if so.
4. Finish the rest of the No Mercy window with Burst Strike with any remaining cartridges, and Solid Barrel combo GCDs otherwise.

During even minute No Mercy windows, use the following priorities under the buff:

1. Burst Strike before entering No Mercy, then weave No Mercy followed by Hypervelocity to get some extra potency in the buff.
2. Use Sonic Break as the first GCD in No Mercy.
3. Use Double Down, Gnashing Fang, Blasting Zone, Bow Shock, and Bloodfest as soon as they are ready. Bloodfest should be used after Double Down.
4. Finish the Gnashing Fang combo, then use the entire Lion Heart inside of No Mercy's buff.

Due to the way the rotation naturally aligns at 2.50 GCD when following this opener, we will sometimes have a situation occur where we already have three Cartridges, our next combo GCD is Solid Barrel, and No Mercy will be ready immediately following the next GCD. At a glance, one might think that the best way to handle this situation would just be to use No Mercy one GCD later, entering the burst window with three Cartridges. This is a common mistake that delays No Mercy and misaligns your burst window from party buffs. The more No Mercy is delayed, the more likely it is to lose a use or partial use of No Mercy as well as the high potency abilities within it. Another common mistake is to use Lightning Shot to keep three cartridges when entering No Mercy. Not only is this a potency loss because you are trading a combo GCD for a weaker potency ability, but this mistake also brings a plethora of other issues to the rotation alignment that will be discussed later.

The correct way to handle this situation is to use Burst Strike, immediately use No Mercy, then late weave the Hypervelocity so it is within the 20% damage buff provided by No Mercy. If this occurred during an odd minute sequence, use Solid Barrel as the first GCD inside of No Mercy. This will put you back at three cartridges so that you can execute Double Down and Gnashing Fang as the next two GCDs. Use Sonic Break after Gnashing Fang, then complete the Gnashing Fang combo. Finish out the window with combo GCDs. If this situation instead occurred at an even minute window, there will not be any room to use combo GCDs inside of No Mercy. Therefore, use Sonic Break as the first GCD inside the buff since Double Down and Gnashing Fang will still be on cooldown. Follow this with Double Down to consume the two cartridges you will have at this point. Use Bloodfest immediately to refill your Cartridge gauge, then finish the window with a full Gnashing Fang followed by the Lion Heart combo. This type of No Mercy window is widely known as a "Two Cartridge No Mercy."

Due to the nature of 2.50 GCD Gunbreaker in Dawntrail, we choose to Burst Strike into an even minute No Mercy window to force a Two Cartridge No Mercy. if possible. This gains additional potency by putting a Hypervelocity inside No Mercy that would not otherwise be there. By forcing our even minute windows to be this way, our odd minute windows will naturally alternate between being a Two Cartrige No Mercy window and a normal Three Cartridge No Mercy window. This makes the rotation a four minute long loop that flows like this:

Odd Two Cartridge No Mercy → Even Two Cartridge No Mercy → Odd Three Cartridge No Mercy → Even Two Cartridge No Mercy → Repeat ad infinitum.

This loop only works if the even minute windows are entered with zero or two cartridges, not one or three, and is referred to as the "0/2 (Zero-Two) Loop" as a result. Using the Standard 2.50 Opener, you will normally see Two Cartridge No Mercy windows. However, "Zero Cartridge Loops" can be done by using Burst Strike before No Mercy to enter No Mercy at zero cartridges. From there, Bloodfest is used earlier, which is a kill time specific optimization that can potentially spend more cartridges before the end of the fight due to it spending cartridges sooner in the timeline compared to Two Cartridge loops. It must again be stated that staying on this loop requires perfect uptime and no rotational mistakes. Even a single lost GCD or Lightning Shot use will change rotation alignment, which can potentially force Bloodfest to be delayed due to being forced into an even minute No Mercy window with a different amount of cartridges than expected. This makes it impossible to continue with the original loop if it occurs.

Alas, we are not machines and we cannot guarantee that we will never make a mistake; what happens if you do lose a GCD of uptime, or have to Lightning Shot because a mechanic forces a disengage? What would happen is that you would be put on a different loop that eventually will force Three Cartridge No Mercy even minute windows. This loop is referred to as the "Three Cartridge Loop." It is possible to spend additional cartridges on Burst Strike before No Mercy, which turns the loop into a "One Cartridge Loop," similar to how the "Zero Cartridge Loop" works. This One Cartridge Loop can still benefit from buffing Hypervelocity with No Mercy, but doing so requires a different opener and is not possible to do mid-fight.

The problem with this is that each loop requires Gunbreaker's cooldowns &ndash especially Bloodfest &ndash to be used in specific places, so switching from one loop to the other requires some adjustments eventually. This becomes necessary at the point of the rotation in which there is a forced cartridge state. This means that you will be forced to have a specific number of cartridges when entering an even minute No Mercy window. For example, the Two Cartridge No Mercy is a forced cartridge state due to being forced to Burst Strike into No Mercy. The specific number of Cartridges you will be forced into will depend on which loop you are currently on. The 0/2 Loop will force two normally, and the 1/3 Loop will force three normally. This forced cartridge state will only occur once every four minutes.

Once this forced cartrdige state is reached, Bloodfest must be delayed to avoid misaligning No Mercy and causing potency losses. This is not a problem in and of itself until you reach the point where Bloodfest can no longer be delayed any further while still executing the window properly. Additional loop swapping after a delay has already been made can push Lion Heart or Sonic Break out of No Mercy, resulting in a significant potency loss. When Bloodfest can no longer be delayed, additional swaps that force a cartridge state will leave you with no other option but to delay No Mercy, which results in misalignment from party buffs as well as a significantly higher chance of losing potency at the end of the fight or the phase depending on how many delays were made, as well as the kill time of the fight. This is the major reason why 2.50 is incredibly inflexible and punishing for any mistakes.

It is possible, however, to swap back to the original loop after experiencing a loop swap if and only if the second swap happens before a forced Cartridge state even minute window. This is not something that should be done intentionally, but it is worth mentioning if fight design, an additional mistake or Lightning Shot causes it to happen. If this were to occur, the player may not notice anything was amiss at all, as they would be back on the original loop they started with, and their cooldowns are already aligned for this loop.

All mitigation in FFXIV interacts multiplicatively, like all other buffs in the game. However, perhaps counterintuitively, mitigation stacking gives less than the sum of the individual mitigations used. For example, using Heart of Corundum does not give 30% mitigation for 4 seconds. Instead, it gives 15% * 15% mitigation for 4 seconds, which equals out to 28% mitigation for the first 4 seconds, and 15% mitigation for the final 4 seconds. This is because the way the game calculates the mitigation in is terms of %damage taken by the player.

This formula is always represented as 100 * (1-mitigation value as a decimal), repeating the * (1-mitigation value) for each individual mitigation source. Using Heart of Corundum again as an example, the damage formula would be calculated as 100 * (1-0.15) * (1-0.15) = 72. This means the player takes 72% of incoming damage, which is the same as saying 28% mitigation, instead of 70% damage taken or 30% mitigation as some might expect. This effect is even more noticeable when stacking multiple mitigations. Heart of Corundum, Rampart, and Great Nebula when used at the same time do not equal 70% mitigation. Instead we again use the damage taken formula of 100 * (1-0.15) * (1-0.15) * (1-0.40) * (1-0.20) = ~34% damage taken, or 66% mitigation. Please note that it is not exactly 34%/66%, as there is some rounding that the game systems do on the backend. However, this is good enough for explanation of how mitigation interacts.

All abilities have some time between when they start their ability clock and when they actually apply the damage. This is called application delay. This delay can be extremely important to know because there are situations where using a higher potency ability on paper is a loss because it ghosts, or in other words the damage does not apply before the target becomes invulnerable due to fight phasing or the target dies. Please note that application delay does not have any effect on whether an ability retains a buff or not. Buffs are snapshot when the cooldown clock begins to spin for instant cast abilities. Especially in the case of Gunbreaker having some abilities with fairly long application delays, it is possible for an ability such as Solid Barrel to be used with the No Mercy buff still active, the buff expires, and then the damage applies. Because the buff was present for the snapshot, the damage will be buffed despite being applied after the buff expired.

Below is a list of Gunbreaker application delays. For abilities that apply a buff, such as No Mercy or Great Nebula, the time between the skill activating and the buff applying is between 0.5 and 0.6 seconds on average.

Skill Name	Type	Delay Length (in seconds)
Keen Edge	Weaponskill	0.89
Brutal Shell	Weaponskill	1.07
Solid Barrel	Weaponskill	1.65
Burst Strike	Weaponskill	0.71
Hypervelocity	Ability	0.76
Gnashing Fang	Weaponskill	0.62
Jugular Rip	Ability	0.80
Savage Claw	Weaponskill	0.62
Abdomen Tear	Ability	0.76
Wicked Talon	Weaponskill	1.16
Eye Gouge	Ability	0.98
Double Down	Weaponskill	0.72
Sonic Break	Weaponskill	0.62
Bow Shock	Ability	0.62
Blasting Zone	Ability	0.62
Lightning Shot	Weaponskill	0.72
Reign of Beasts	Weaponskill	1.16
Noble Blood	Weaponskill	1.65
Lion Heart	Weaponskill	1.79
Demon Slice	Weaponskill	0.62
Demon Slaughter	Weaponskill	0.62
Fated Circle	Weaponskill	0.54
Fated Brand	Ability	1.16