I'm sure you have seen this spec around. This is currently the undisputed spec for M+. It has raw AOE output, burst or sustained, that NO OTHER class can compete. This alone, along with Death Grip and Brez, should makes you desirable for any M+. This going to be a quick TLR guide. For the uninitiated, this is how it goes
[Intro]
This spec is heavy AOE spec. When it comes to AOE, you should always be top dps. It still does relatively well in single target bossfight, however you cannot compete with classes who are specced for ST. This build abuses icecap and Frostwhelp Indignation. With triple Indigation traits and icecap, you are going to throw out massive AoE burst every 15sec or so. Frostcythe and Murderous Efficiency will ensure you are never rune starved and continues to trigger icecap
[Azerite Talents]
Frostwhelp's Indignation. All three piece should have this.
Icy Citadel. Aim for at least one
Frozen Tempest. Aim for at least one IF you are running Gathering Storm
Personally my pieces are 3 x Frostwhelp, 2 x Icy Citadel, 1 x Frozen Tempest. This mean, you are looking for very specific Azerite gears.
[Essence]
Main: Blood of the Enemy Rank3, no substitute. Farm it.
Minor: Lucid Dream
[Talents]
Cold Heart - This talent should provide you some single target damage. Aim for overlaps between Unholy Str/Pillar/Icy Citadel. 150k crit should not be uncommon
Murderous Efficiency - A must for this tier because you are going to take FrostScythe and Icecap. Frostscythe uses only 1 rune from Killing Machine. Along with Lucid Dream Minor, you should never run out runes.
Blinding Sheet- Doesn't matter what you take. I like Blinding sheet for the mass aoe interrupt.
Frostscythe- A must for this tier. Together with Murderous Efficiency, frostcythe will enable your icecap to come off cooldown pretty quick.
WraithWalk - Personal Preferences. Death Pact is good when you pull too much aggro from all the big AOE crits. I prefer Wraith Walk as it allows me to get from mobs to mobs faster.
Gathering Storm/Frostwyrm Fury - Frostwyrm Fury is great for Burst AOE and it is easier to play. Never underestimate the damage potential from BoTE + Frostwhelp Indignation + FrostwyrmFury. Gathering Storm provide more sustained AOE and ST damage. Overall, Gathering storm will provide higher DPS IF you play it correctly. As you will be spamming FrostScythe, remember to Obliterate once or twice to ensure Gathering Storm can reach 10 stacks. Take one Frozen tempest azerite trait if you are running Gathering Storm
Icecap - Your bread and butter. Frostscythe/Murderous Efficiency will ensure pillar will come off cooldown very fast. You can throw out HUGE dps with triple Frostwhelp's Indignation. The mastery buff will provide more damage for Frost Scythe.
[Stats]
Crit : most important stats. Aim for 25%<
Haste: while not as important as crit, try not to neglect it. You will still need enough haste to throw as many Frostcythe as you can. Go for 15%<
Mastery : take what you can get.
Enchant/gem for crit/haste. Whichever you are lacking.
[Playstyle]
AOE
rotation will always be
BotE => Pillar (Frostwhelp) => Frostwyerm Fury => Remorsless Winter
All Killing Machine should be spent on FrostScythe.
Spend all Rime procs Asap.
If you are taking Gathering Storm, throw in one or two Obliterate to get 10 stacks. You will not get to 10 stacks simply by spamming Frostscythe, unless you have Bloodlust or other haste boost.
Your biggest challenge with this built is TO NOT PULL EXTRA MOBS with Frostwhelp Indignation. Don't be a noob.
Single Target
Save your Cold Heart to properly line with Unholy Str and Pillar, pop Blood and go for 150- 180k crit. Under BotE, your frost strike should be dealing massive 30-40k DPS too. You should not fall behind too much in boss fights against other dps who know what they are doing.