Cockatrice is one of the strongest, if very random, allies in the Millenium set.

This +4 ally can send an opposing champion to the Abyss, giving instant victory to the using player. This is more likely when the champion level is low (better than 50% chance of Abyssalizing when champion level is 6 or less). However, there is also the chance of losing the Cockatrice permanently to the Abyss if the roll is exactly equal to the opponent's level. This is most likely to occur when the opposing champion's base level is 7 (a 16% chance). This risk is still very low, and only destroys the ally, not the allied champin, and therefore makes this card very worthy.

The only other card the is better against low level champions is the Intellect Devourer (86/3rd), which instantly kills champions of base level 5 or less. If Cockatrice is combine with Rigged Dice (22/MI), this spells instant victory against all champions base level 11 or less not immune to ally powers.

The best defenses against this evil lizard-bird include immunity (like Infyrana the Dragon (26/DR)), preventing the ally from being played (like Net of Entrapment (217/1st)), or destroying it before its power can activate (like with Airship (90/3rd)).

This card will show up in many tournament and non-tournament decks, since it is very powerful and can be used by any champion.