I think the devs said they are working on an in-game report feature. Until then, just ignore them I guess
I don't think they have talked about it, but my guess for long term solutions based on other games is a temp-ban followed by a permanent ban if they get reported again. While still in closed beta though I think they should just jump straight to a perm ban for player abuse. Volunteer testers shouldn't have to put up with that.
We're currently working on an in-game reporting system that will lead to bans (both temporary and permanent). In the meantime, please send reports to our support email address (support@cardhunter.com). Please *don't* post reports on the forums. Sorry for the annoyance until we get this system in place.