You'll need "Siegesmith Bombs" from the quest "Bombard the Ballistae" in Dragonblight.

If you throw Siegesmith Bombs on mobs they will gain aggro on you, and the bombs require no LoS to be thrown (meaning you can throw them through walls and such).

Also, they can be thrown at corpses to trigger combat (Disengage) and Aspect of the Viper (Free mana) and probably other procs from other classes (Seals, maybe poisons and such).