Surtr in 30 orbs or so. +Atk -Spd, holla.
Surtr will be really good for Chain Challenges. Just having a flat 20 damage and -4 stats per turn guaranteed will help for those Lunatic CCs that just pile on the stats to the point you couldn't ordinarily keep up.
I'm using a team of Veronica, Surtr, Micaiah, and Ophelia right now for CCs and it works really great. Tactics viable so Surtr gets even more bulk, a dancer that can bust armors and cavalry better than Surtr can, a healer that provides Close Guard for even more bulk, and a Rally Up Atk partner that gets to use her Blazing special every map with QP seal because Micaiah's here, to instantly remove a threat. A really synergetic team that produces results.