Firecurse

 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 during the card's turn.

Strategy
To make best use of this ability you need to pay attention to your card order! Make sure the ability is activated before you deal fire damage. Check the Turn Order article to see in what order your abilities are activated.