[caliaca]

Isn't this the problem with any Invocation, they just aren't good enough to actually use? Maybe if Charge Mind were to effect ALL invocation or maybe Invocationg et a 3x boost instead of a 2.5x boost.

No, that's not really the problem here. Mist can get pretty decent value in late game stuff since everything takes 1 turn to reach you regardless, essentially letting a lot of invos just be free value.

There's a lot of incredibly good invocations in the game and something like Isenshi now getting a 3x boost instead of a 2.5x boost would likely be absolutely absurdly overpowered.

Anyways, the real problem here is late game mob scaling having too much hit. The reason only half filling up evade bars feels bad is because unless you're above 205 (full 50) you're not really going to dodge anything or even really get glances. 
What actually needs to change isn't Mercalan Mist but removing boss hit by 10-15 and mob hit by 10-15 as well.