Yea, it is considered cheap to use Shade, Shadow Conjuration, Cleric Domain and Epic spells just to bypass spell mantle.
Somehow, these spells aren't recognized as spells by the spell mantle (and spell resist I believe). Bioware screwed up almost every spell in the game when they made HotU.
For example, in my mod "Smith Hold" there was a secret you could uncover using a certain spell on a certain creature. When HotU came out, the Bioware noobs had removed the line that signals the spell event for a BUNCH of spells. So the creature never noticed a spell was being cast at it and this prevented the secret from triggering.
It was a simple fix, but there are hundreds of spells in the game, so fixing them all is a daunting task and fixing them in one module only fixes them for THAT mod.
Bioware really needs to get off their asses and fix this shit.
-420