It's kind of a chore but you can farm successfully on android. not sure how similar iOS version is though. I found that deeper well didn't work so well for me, but I can do pretty well on magus quarters, hard difficulty, survival mode. Playing through level 10 will get you a few hundred thousand mana so you can get the pets in (relatively) short order. Or you can spend a few bucks; I will admit that I've been tempted at times to do that.