[Jasper]

Barksin has always been good, and even better on troops with good armor. It only sucks on things that normally have a high natural protection.

Mass Protection is alot of bang for 1 gem, plus the armor benefits can stack with Growing Fury.

Single castings of Protection/Barkskin can also be effective on things like Elephants/Hydra, or Sidhe commanders. In particular the synergy with Regeneration is nice.

In Dom 1 I fairly often would give important armored commanders Barksin amulets, as the extra protection made them much more survivable against mundane troops.