Innas Guardians (spelled that way instead of Inna's Guardian in-game) are Unique Colossal Golgors found in the Inna's Mantra Set Dungeon in Diablo III.
In combat, they have the Frozen affix. One of the objectives is to never get hit by its final freezing blast. Receiving damage over time from the pre-blast crystals will not fail the objective, yet may easily kill the Monk.