I use Obey on both fairies. I have read quite a few people saying to leave Selene on 'sic.' That just seems like a waste to me. She will cast Fey Light/Fey Glow off cooldown, but will often waste it. A good example is during turn 9 during the golem phases/meteor placing. When you are just standing there waiting for meteors to drop, it is a huge waste if Selene is like 'lol buff skill time!' when there is nothing to attack. You want to get used to controlling those abilities manually.