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 is an active ability, which means it will only activate once the creature has a full bloodlust counter.  For a list of all Cards with this ability, click here! 

Variations
can appear as certain activation, or with a chance to activate. It will always activate at the end of your turn.

Strategy
Most creatures with this ability are pretty tanky, with lots of health, or Tougness and Diamond Skin abilities. This way, they will be able to block enemy attacks for quite long, while allowing your weaker creatures to attack possibly yet inactive enemy creatures.