Taren Seeker said:
The real nasty part of this feat:
-Earth Dreamer with the walk/see through walls ability
-Initiate of the Sevenfold Veils walking out of his area veil then back in
-Wizard with Ghostform running.
-Wizard behind his own Prismatic Wall/Sphere
-Wizard hiding around a corner, casting every round and claiming full cover
-Wizard/Rogue type throwing sneak attack spells then moving/hiding every round.
-Wizard/Monk/Enlightened Fist essentially spring attacking with his touch spell ability
The Concentration check limits this feat at lower levels, but once you get a good concentration score it's all gravy, made from CRACK COCAINE.
This is what I wanto analyze: at first it seems broken.
OK, a Wiz 9 with good Con (18 with items) will have a concentration check of +16. Adding Skill Focus Concentraion*: +19
His highest level spell has the following:
Cast Defensively: DC 15+5=20---------> 100% succes rate
Cast on the Move: DC 20+5=25---------> 75% succes rate
Cast Def/Mov: DC 25+5=30---------> 50% succes rate
Here it seems balanced, in the sense that he still loses the spell on a failed attempt, and the cases you mentioned involve the lowest succes rate.
OK now a Lev 13 Wiz will have a +23 Concentration check, but the DC are now 22,27, and 32 meaning the succes rate is now: 100%, 85%, 60%. Better, but not game breaking.
A lev 17 Wiz: +29 (more con as well): DC 24,29,34 --->100%,100%, and 80%-----> pretty good. But he's a 17th level wizard anyways, with a feat "wasted" on this.
* I'd allow the +4 of Combat casting to apply on all Mobile spellcasting checks as well. Probably use it as prerequisite as well.