Costumes coming next month will improve Boril (better stats AND the chance to get him to functionally fast) and Cyprian still awaits his so THAT issue is parked for a bit. That said, Cyprian is perfectly acceptable when emblemed, his stats can be on par with many 5*.
Elena - exactly as the quote you put in from Suicide Bunny, she is weird, massive attack stat, extremely low health and slow mana. I maxed her for titans, her tile damage is excellent but you need to watch her closely to ensure she doesn’t die. If you are able to give her emblems she can become more valuable. I believe the idea would be to accentuate the enormous attack stat and fervently hope to summon her costume too.
Raids I cannot speak to, she came to my team late and was a luxury item and I already had heroes that I prefer in PvP battles.
@IvyTheTerrible has done an enormous amount of work on her raids vs various tanks and Elena holds up well: Raid Data
Here she is speaking about Isarnia who is very similar to Elena in that she is slow mana, low defense with a devastating special and at the end mentions Elena:
For OP @Talzemorden_Knight , you never mentioned what role you would have her perform, on defense Tank is probably the only spot you can expect her to fire and in that spot she may not be the best in the entire game but she can be effective. She’ll punish bad boards hard and die quickly on good boards.
She’ll help you on titans.
Good luck gathering the materials, that is the eternal quest.