Collectible Card Game Headquarters

Describe the Bug:
When player cast Ancestral Vengeance on target creature, game will put a -1/-1 counter on it then ask to target a creature owner but will put a +1/+1 counter on the one who got the -1/-1 counter instead.

Which card did behave improperly ?
Ancestral Vengeance

Which update are you using?(date,name)Which type(Duel,Gauntlet,Sealed Deck)
Manalink 2015/3/25: Fate Reforged,duel

What exactly should be the correct behavior/interaction ?
When player cast Ancestral Vengeance on target creature, game will put a -1/-1 counter on it then ask to target a creature owner and will put a +1/+1 counter it

Are any other cards possibly affected by this bug ?
-

Confirmed,although you target a creature of your own to give the +1/+1 the bonus still goes to the enchanted creature.

Also AI can cast Ancestral Vengeance with only a creature of mine Cetavolver 1/1 on the battlefield.

Actually, I don't think that is a bug. Since you only pick the target after the enchantment enters the battlefield (when the enter the battlefield ability triggers) you can cast it without a valid target for that ability. The enter the battlefield ability will just fizzle when it triggers.

Fixed first bug reported in c457bda