You are a Troll
Yeah….seems fairly silly to change something like this (and only this) for moving to OE, but hey, the Inner Circle likes their Chill Touch Mage Cheese despite whatever their PR smokescreen people might post here and the game must bend to their will. This is the way.

Any chance of failure on the chill touch drain is deadly at T3 regardless of 50%, 75% or 95% success you eventually will charge in to melee, fail to drain and die - so it renders the strategy totally unusable. It was just the wrong way to balance the effectiveness of chill touch (unless the intention actually was to stop people using it altogether).

If the issue was the amount of healing it provided, a more suitable way of balancing the chill touch/devourers combo is to reduce the healing (already done) and maybe fiddle with the amount of drain applied (potentially needing drain to be refreshed with a new chill touch more often). Adding a failure chance to the chill touch drain was not just a nerf it made the entire strategy nonviable.