Tai vs Dungeon- I was all set to vote against him, then thought "wait, Rika can nuke everyone's speed and give Crowly and Eiko a chance to actually kill stuff". Seems effective.
Piggy vs Dungeon- This feels like the point at which Magus' damage should level off a little (as the normal cast would get L1 spells at this time, which in terms of damage are no different from L2 spells), so while still good it's no longer dominant. And... well. Piggy's only got Ben for reviving duty and I don't think he can stay alive through the whole floor.