The mod 6 Sentinel feat tree has awesome increases in aggro generation so it has great potential to be an off tank. Just one problem, he can't tank. He might be bale to take a hit more than a Destroyer build but that's no consolation with all the mobs you draw with that extra aggro and with the lower damage output you'll…
That's my understanding thus my not going for a high role on CON. AP gain for dailies is always useful especially as you don't get AP from enchantments, but those Crit heals sound awesome. Dragonborn is certainly appealing for the stats although 3 extra feats is useful too. My choice of human is more a thing from my RP…