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)
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Raid Schedule:
Tuesday - 8:00 PM EST - 11:00 PM EST
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We add a Monday raid to the first week of each raid tier.
Holidays will be rescheduled.
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High Priority:
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All classes will be considered even if not listed in this post.
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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.

Welcome Adventurers! The time has come upon us, FINALLY! The moment in Classic WoW history us diehard, loyal WoW nerds have all been waiting for. WRATH CLASSIC! Arthas Did Nothing Wrong (ADNW) has just begun recruiting (For WotLK Classic) hard-core, casual, rp, pvp, pve, raiders, anything you can think of, you are welcomed here. Although our main focus in ADNW will be progressive raiding, 10 and 25 man and pvp content, we look to have someone for just about anything. Currently we are recruiting for our CORE 10M team composed entirely of irl / internet homies. We are in need of just 1 HEALER (Highly prefer a disc priest with a shadow off spec) and another DPS. Preferably lock or Shadow priest. We are looking to fill our B 10m team entirely, so we can pool together for 25 man’s when it comes time to crush 25m. This guild was founded by a group of tight nit friends recently, who have been around since TBC. WOTLK was our turning point in WoW, and we CANNOT wait to get another crack at this and MAKE IT RIGHT. Come join the adventure of a chill environment full of helpful hands and knowledge. Feel free to reach out to me Via Discord: Daevilmonkiexp#9239 OR Bnet: Daevilmonkie#1280 just let me know you are interested in the guild and we can have a convo! ARTHAS DID NOTHING WRONG!