I just worked my life bat to ancient and thought that it would provide health to the group on it's own. To my disappointment it is a card you receive that costs two pips to cast. I did all that work to find out out I could just use the unicorn spell I have.
Can you change it so life bat will cast on it's own like the pets that cast sprite? Then it is worth the effort to get to ancient level. Right now I would tell people to not waste their time.
The life bat gives a card unlike the talent spritely. Maybe they could make it similar to the fierce hound with a new talent called "life bat." The pet would always receive this talent at ancient.
Your right though, if the life bat is only 10+90 over three rounds for a card a ancient, the pet or the spell needs to be powered up or the pet should give the card at teen.
Notice, the card sprite heals a total of 300 for 1 pips. So maybe the life bat card should be 50+300 over three rounds to all friends for two reasons. One its a pet that is hard to get and takes awhile to train to ancient so the card it gives needs to be worth your time. Two, sprite costs one pips so for one more pips, like attack spells, it should be turned into a heal everyone card. (humongofrog does the same damage as cyclops but its an AoE for one more pips.) So the card needs to heal around 300 (I made it more then 300 for the first reason.) Also you can only have one of these in your deck whereas sprite you can have up to 7 (if you a life wizard.)