Im playing rogue assa in cata classic and after read some guide I don't understand some things about stats. 
I know as a rogue assa I have to priories hit rating until the spell hit cap of 17% (1332 if I remember) but i dont understand how to manage other stats like mastery and haste/crit or expertise. 
Did I have to put full mastery ? and reforge all the crit chance, expertise and reforge haste at least ? Or did I have to balance mastery and haste ?
Can someone help me to understand in wich ordre and priority I have to manage stats as Assa Rogue in wow cata classic ?

As the title already said I'm needing help understanding how to make the build like the guide says, i somehow need to get the full set bonus of bones of Rathma but i also need the full Captain Crimson's trimmings bonus for cd reduction i can get that with ring of royale grandeur but i also need to use fate's vow helm but if i use it i cant get the full Bones of Rathma set bonus or Captain Crimson's trimmings bonus. 
If anyone know how i can get that build to work please say how, I'm open to any suggestions.
Link to the guide I'm  talking about: https://www.icy-veins.com/d3/necromancer-rathma-army-of-the-dead-build
(this is my first post on icy-veins and i don't fully understand if I'm doing this right) 

Children - Zul'jin - Horde - 3 nights/week (9 hours) - Hardcore
Vault of the Incarnates - M 8/8 (Cutting Edge)
Sepulcher of the First Ones - M 11/11 (Cutting Edge)
Apply here!

Raid Schedule:
Tuesday - 8:00 PM EST - 11:00 PM EST
Wednesday - 8:00 PM EST - 11:00 PM EST
Thursday - 8:00 PM EST - 11:00 PM EST
We add a Monday raid to the first week of each raid tier.
Holidays will be rescheduled.
Current Recruitment Needs:
High Priority:
• Enhancement Shaman
• DPS Death Knight
Medium Priority:
• Rogue
Low Priority:
• Healers
All classes will be considered even if not listed in this post.
Server Information:
Zul'jin
Chicago Datacenter
Eastern Realm Time
Contacts:
Battle.net: Madness (Madness#12309) / Discord: Madness (Madness#5716)
About Us:
Children is a guild founded at the start of Shadowlands, we accomplished CE in all three raid tiers during the expansion, also obtaining CE in Vault. We are looking to continue this pattern for the rest of Dragonflight, and are looking to pick up new members to join us. We look forward to hearing from you.

This thread is for comments about our Outlaw Rogue Leveling Guide.

<Fun is for Casuals> is a serious but casual horde guild on US-Hyjal. We are serious about raiding without the intense hours. Even when recruitment status is none, we will accept exceptional applications for all classes.
Our raid times are Tuesday and Thursday from 5:30PM to 8:30PM server (PST) with raid invitations sent out a few minutes prior to that.
We're interested in you if you fit the following criteria:
Raid attendance is essential. We don't want people sitting on the bench but we also want to make sure we're raiding 6 hours per week. We expect you to be available for at least 90% of our raids. Be on time and prepared for raids. This includes flasks and other consumables. Discord is mandatory and a working mic is desired. You're appropriately geared for our current content. Effort and thought have been put into your gear/gem/enchant choices. You wouldn't show up for a job interview looking like a *filtered*, why would you apply to a guild with improper gems or some insane spec? You're up to date with your class. We expect our raiders to perform to the best of their abilities. You have a computer that's not run with hamster power or requires a hand crank. Some encounters are taxing on a computer's resources so if your toon can't even handle Orgrimmar it's not likely to do well with 20+ whelps that need AOE'ing. You may be interested in us because:
 <Fun is for Casuals> uses the personal loot system. There is no loot council, or DKP. We won't eat your babies the first time you stand in something you have no business being in. Repeatedly do it and we'll break out the bibs and BBQ sauce. We provide a limited amount of consumables and flasks on hard mode raid nights.  Discord isn't a circus during raids. We're focused on the job at hand and you should be too. We don't want someone to miss a an interrupt because they were distracted by fart jokes. We are not interested in you if you fit the following criteria:
You roll on BoE items then sell them. Unwilling/unable to spend an entire evening on one boss during progression. While this is rare, it can happen. Drama queens. If you have a problem bring it up to E. This is his job. Don't announce it in guild chat or during a raid. Your issue will have nothing to do with 99% of the guild. You are 17 or younger. We try to keep guild and discord chat PG-13 but occasionally a few four letter words appear out of nowhere. Additionally, we don't want someone's mom interrupting their raiding to get homework or the dishes done. Follow the instructions at https://gow.gg/fun-is-for-casuals under the Recruitment tab if you would like to apply.