The only thing merging does is give a level up (same rarity only), give some SP, and make the cost of increasing their star count go down a very small amount. Abilities and stats of the 'sacrificed' unit don't add anything to process.
So how did everyone do in the arena? I ended up with 3,500 feathers. My rank went from 4,000 to 11,000 overnight so I missed out on 1k feathers I was initially up for.
It seems like the key to getting a good rank is 1) Win 7 Advanced battles in a row, 2) Don't let your units die during those battles and 3) Use as many of the seasons bonus characters as possible. I had a few arena battles where some units died and I only used one bonus character so my score probably just wasn't good enough.
Good to know for next time though.
edit: Also, prepare for 10k free feathers.
So how did everyone do in the arena? I ended up with 3,500 feathers. My rank went from 4,000 to 11,000 overnight so I missed out on 1k feathers I was initially up for.
It seems like the key to getting a good rank is 1) Win 7 Advanced battles in a row, 2) Don't let your units die during those battles and 3) Use as many of the seasons bonus characters as possible. I had a few arena battles where some units died and I only used one bonus character so my score probably just wasn't good enough.
Good to know for next time though.
edit: Also, prepare for 10k free feathers.