This was another case where rental was really helpful as I don't own eels, but I was also skeptical since I didn't think they would be really valuable in any of the ways I would normally use water, so it took a lot of time to actually find an appropriate fight.
This one had limited splinters (water and light), moderate mana, and limited to even monsters.
Really I won by relying on sea monster surviving (the coral wraith taking out some backline helped a lot). The eel contributed very little and probably would have been better replaced by any number of others.
Because this wasn't too exciting I'm keeping it short.