Ice Block and Blink should be used to avoid lethal damage and to clear debuffs or handle mechanics when it’s safe.
ToC
Faction Champions — avoid lethal damage and physical CC; Blink away from melee; use Frost Nova to control them; Spellsteal enemy buffs.
Anub’arak — clear a debuff in Phase 2 when appropriate, and Blink away from spikes during the transition.
ICC
Lord Marrowgar — avoid Coldflame.
Lady Deathwhisper — avoid Summon Spirit; Polymorph casters who get Dominate Mind by the boss.
Deathbringer Saurfang — remove the Boiling Blood once per fight when appropriate.
Rotface — avoid Ooze Flood.
Festergut — Ice Block Vile Gas; Blink away from Malleable Goo.
Professor Putricide — avoid Slime Puddle, Malleable Goo, and Mutated Plague.
Blood Princes — avoid Conjure Flame and Shock Vortex.
Blood-Queen Lana’thel — avoid Swarming Shadows.
Sindragosa — manage Unchained Magic and the pull-in; use Ice Block for Frost mitigation when handling Ice Tomb and during Phase 2; catch an Ice Tomb in Invisibility (requires practice).
The Lich King — avoid Shadow Trap, take Necrotic Plague out, avoid Vile Spirits and lethal damage, and take Defile out of the raid.
Ruby Sanctum
Blink back in after you drop the debuff.
Extra note
Blink also breaks movement-impairing effects (slows, roots, Frost Nova, etc.).
