The main duties of a Shadow priest in a raid

Lord Marrowgar

• Use Divine Hymn when the raid takes heavy damage (especially if healers are in spikes).

Lady Deathwhisper

• Fear mind-controlled players in the ranged camp.
• Use Divine Hymn in critical situations (lots of ghosts in melee, healers are MC’d).
• You can help dispel slows on targets.
• Use your Hymn of Hope as needed.

Deathbringer Saurfang

• Use Divine Hymn in critical situations (multiple Mark targets).
• Use your Hymn of Hope as needed.

Festergut

• You don’t have to catch the spores — you can survive Gastric Bloat with Dispersion.
• Use Divine Hymn in critical situations (for example, if healers get hit by the "vomit").
• Use your Hymn of Hope as needed.
• Festergut is usually killed after Rotface, so you may need to start the event before Professor Putricide and clear the bugs.

Rotface

• You can DPS while standing in a slime puddle (BUT if you have the disease, it must be dispelled).
• The small slime can be Feared.
• Use Divine Hymn when the raid is in critical condition (raid is vomiting, slime explosion).
• Use your Hymn of Hope as needed.

Professor Putricide

• In phases 1–2, you can DPS while standing in a slime puddle.
• Divine Hymn may be needed in the last phase.
• Use your Hymn of Hope as needed.

Blood Prince Council

• Use Divine Hymn if the raid drops low and needs topping.
• Use your Hymn of Hope as needed.
• After killing the princes, on the trash packs you may need to assist with Mass Dispel (removing chains or bugs).

Blood Queen Lana’thel

• You can take the flame to the wall and pop Dispersion — this makes healing easier and reduces how much fire gets spread.
• Put Fear Ward on the flame target before the air phase (decide in advance who’s responsible).
• You can also put Fear Ward on the player who’s getting the first bite for logs (also agree on this beforehand).
• Use Mass Dispel during the air phase to remove Fear.
• Use Divine Hymn in critical situations (air phase, a healer dies, someone is carrying the flame).
• Use your Hymn of Hope as needed.

Valithria Dreamwalker

• Use your Hymn of Hope shortly after the start.
• Use Divine Hymn during the final heal-up on the boss.

Sindragosa

• We dry the ice tombs, don’t put DoTs on them (there’s a risk of breaking them if people are nuking with the red-eye debuff). You can use Mind Flay as well.
• You can stack Unchained Magic up to the grip (if you have Dispersion), then run off in the opposite direction and detonate your stacks there — it’s important not to hit the raid.
• Use Divine Hymn in critical situations.
• Use your Hymn of Hope as needed.
• If you kill her in a single air phase, save Shadowfiend for Bloodlust.

The Lich King

• Dispel Necrotic Plague from yourself. If you’re far from the Shambling Horror and don’t have speed boots, you can survive one tick of Necrotic Plague with Dispersion.
• During Remorseless Winter in transition phases you don’t have to run after the ranged group right away:
  • stay and DPS until the last moment,
  • then pop Dispersion and run to the edge (extra boss damage + mana regen).
• In the transition: kill Ice Spheres, DoT the spirits, and do as much damage as you can.
• Use your Hymn of Hope as needed.
• Divine Hymn is usually used if healers get carried off by Val’kyrs or if there are issues with Infest.
• Inside the room (Frostmourne): “dry” the spirits (no heavy DoTs), you can poke them with Mind Flay.
• Outside: you don’t have to stack with the raid when the spirits are flying in. If they fixate on you → Dispersion.
• If you’re asked to soak spirits: wait for the boomkin’s Typhoon → use Dispersion + speed boots and blow up the spirits.

Halion

• Play with the Glyph of Mind Sear (mandatory in ICC and RS).
• A big elemental + a pack of small ones spawn.
• Channel Mind Sear on the big one to pick up the small adds.
• When they cross to the boss’s side and get close to you → hit Dispersion to drop aggro onto the off-tank.
• If you’re assigned to put a shield on the main tank during the run — do it.
• If you’re assigned to dispels — dispel the targets. If the debuff is on you → remove it yourself.
• In the shadow realm: DPS and use your Hymn of Hope after the second cutter (if assigned).
• In the physical realm, in the last phase there is no Replenishment → you have to provide it yourself by casting Mind Blast on your Vampiric Touch target (refresh it often, since the buff only applies to 10 players per application).