Congrats! xD
But yeah, keeping the sheep alive is really hard. The best strategy is reviving it when the ogre is close to death. It's no coincidence you find unicorn tears in the dungeon right before the farm ;)
Skeletons are probably immune to blind since they don't have eyes, tho the lich can be silenced (I think, been ages since I worked on the game lol). But bosses tend to have high resistances to debuffs because it's 3x1 and stun-locking it would be too easy otherwise.
Anyway sorry for the headache! The game isn't meant to be super hard or anything (you're actually expected to not do every mission perfectly) but learning about elemental resistances and not just spamming attacks every turn is important. You can always check the book in the guild too for tips against pretty much every enemy in the game too!
