Shaman · Restoration · tier 3 · from level 20

Healing Focus

Rank 3/3

Gives you a 70% chance to avoid interruption caused by damage while casting any healing spell.

Doesn't change the damage or healing of any Shaman spell.

Averages, counting crits and misses, for a level 60 Shaman with a typical weapon and no other gear or buffs, against a target your level. Worked out from the game's own data, the same way as the Foresight addon.