I've been merging 4-star Cain whenever I wind up pulling him from any banners with red focuses(sometimes I forget to keep him around for my refresher units, too) and he's looking pretty good at +6 right now. With that many merges, it even drops the cost of feathers if I ever decide to promote him to 5-star(which I'm not).
This leads to Ogma, a 5-star pity breaker who screwed me over when I was trying to get Elincia during the Death Blow banner with her, Klein, and Delthea. Since I really have no use for him and his HP+/Atk- IVs, I was thinking about just foddering him off to Cain for his Brave Sword+. I did the same to a pity breaker Abel during the Christmas banner, feeding him to Effie who makes better use of his Brave Lance+.
In short, is it worth it to sacrifice Ogma to my Atk+/Res- merged 4-star Cain?
I think it's worth boosting the power of characters you like to use. If that increases your experience of the game, then, by all means.
Obviously, there are units better suited for this role. Also, Cain has Wings of Mercy 3 at 4*, which is a coveted skill by many units, so I wouldn't have used him in the first place.
I accidentally merged the last Cain I had summoned during the New Year banner, forgetting about using him for NY!Azura. I was so desperate for Wings of Mercy I promoted a lousy IV Palla for it, which wasn't too bad since I always sent home any units I either had no use for or they had lousy IVs.
Cain is just so common at times for me that I'll probably make him the first +10 4-star for me to use. If I get more Ogma, I can save them for other users who can utilize a Brave Sword better.
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