Don't go wasting orbs until you're done exchanging Kaisers.. - is what I'd like to say, but Tiamat is kinda an exception, if you don't have an MLB copy of her. Useful active, amazing stats & works as a main eido, too. You'd use her on every eido grid unless you're a sea creature.
But srsly, otherwise Kaisers should be the prior target. Don't bother with previous raid eidos until you're done exchanging them. Their active is just way too useful & even at 0*, they got good enough stats to not make you lose too much stat.
Also, forget about accessories, SR stuff & anything other in shop, unless you really like memeing. Maybe HEs if you're in need of some emergency supply to finish some advent event.
Wut u smokin'?