Ankh is an item added by Project Zulu. It is only available as a boss item drop from the Pharaoh boss. Right-clicking with it will hurt the player by half a heart () and create a fireball at the top of the world headed towards the user. If the damage caused by the Ankh would kill the player, it will not activate. It is useful to fight groups of mobs or grief others.
The Ankh can be used when chased by multiple mobs, as the fireballs will fall where you were, possibly where the mobs now are.