cancelling ability

[concorde]

I click devour on a scarab only to find he can't eat anyone anyway, so I click cancel only to lose the ability to recast if I drop a weaker creature and I lose the energy point so I can't use that for other casts or drops. I've noticed this on scarab and toadfish so far.

[Cynxos]

This is a pretty much known bug, and I promise you that you're not the only one whos aggravated with it.

[Kamietsu]

As far as I know, this isn't a bug. Well originally it might have been, but that's how it works with any ability and then you cancel it. Think of it as a penalty for not checking ahead of time, especially the Oty. I never activate the ability unless i know exactly who I am going to eat. It's stupid to rely on the game telling you what you can and can't eat when you can look at the cards yourself. You should know when you should or shouldn't use your ability.

[Delreich]

Well known, and should probably be added to the known bugs thread under "not bugs" (along with generating a critter when the board is full) until it's changed.
I've voiced my opinion on this before (http://elementscommunity.org/forum/index.php/topic,1677.msg17669#msg17669), and I really do hope it gets changed. Calling your users stupid because of flaws in your interface is not exactly user friendly.

Similar but not yet cleared as intentional: if you misclick on flying weapon when you don't have a weapon, you lose the quanta (but not the card).
If you try to hasten with a full hand, you lose the card you would have drawn and the quanta used (already in the known bugs thread).