Teammates for Merric?

Hey guys, I'm thinking about making Merric a merge project once I finish my current on. I already have a main arena core so he'd be more of a project I'd do for fun. As far as resources go, I have a fair amount of 5*s I'm willing to sacrifice so I'm open to any build suggestions. And to make it more fun, I may even make it an all mage team to not only get the most out of his tome but because I really don't use very many mages aside from Soren and occasionally Reinhardt/Celica so it'd be a nice change of pace for me.

As far as his build, I was thinking of give him a standard Close Counter build with QR & Close defense seal so he can act as a decent tank, maybe Infantry Pulse for his C-slot if I run an infantry team.

For his teammates, I'm thinking about pairing him with M. Morgan as a support. Merric would appreciate the effects from Grima's Truth. Not too sure what build I'd run for him. Maybe a Windsweep build or a Close Counter + Vantage build?

Finally, for the last slot, either Tailtiu or L'arachel as offensive mages. Leaning toward Tailtiu for an infantry team and she'd appreciate buffs for a typical blade tome build. And also because I prefer Tailtiu as a character.

Any suggestions are appreciated.