LA!wood, merge or fodder

The only person that can answer that question is you. I wouldn't necessarily merge simply because there's, at the moment, only 2 LA!Eliwood's that each account can have, so merging him would be kinda pointless in many cases.

You can keep one and, if you really want to, fodder off the other one, but just know that the possibility of being able to obtain a seasonal Tempest Trial unit again outside of said original Tempest Trial hasn't ever been done if memory serves me right.

For the Tempest units I always keep the 5 star one and foddered the 4 star or sent them home (such was the case "Marth", Tobin and Clive). At the end of the day it's really up to you what you're gonna do with them.

For me personally I don't want to fodder Him cause He really doe'snt have any good skills except for goad armor but I don't have any unit I want to have goad armor.So in the end You should really just decide wether to merge or fodder him If you really like him Merge him if you don't then keep one and fodder the other.

Merge. Can't see why you'd want Casa Blanca on anyone else, and armor merges with that BST adds up well in Arena.

I think the only another unit that deserves FireBoost is Arden.