The caster heaves back, and then spews a boulder from their mouth. The boulder travels a short distance before arcing towards the ground. If a foe is hit by the boulder during its travel arc, they will take heavy stagger, being knocked down if they are smaller enemies, and take 1.8 times the Spell Buff of the catalyst as Physical damage. When the boulder impacts with the ground, it will shatter in a moderate radius and inflict 1.1 times the Spell Buff of the catalyst as Physical damage to any nearby foes, as well as moderate stagger.
When used against blocking opponents, the boulder's impact causes large stamina damage, potentially breaking their guard.
Due to its low requirements and FP cost, Boulder Heave is a very effective Pyromancy if used correctly. It can stunlock certain foes if timed properly, and the shatter's area-of-effect makes it a handy tool for dealing damage to crowds of enemies. As well, large enemies with spacious hitboxes and standing Poise, such as most bosses, will not be knocked down by the arcing boulder, meaning that it is possible to hit them with both the boulder and the shatter, dealing the spell's full damage.
The main draw of this spell is that it has the same animation as various mist Pyromancies like Poison Mist and Toxic Mist, which allows it to be used to catch opponents who expect to run around a mist cloud but instead take a boulder to the face. However, as the spell is very short-ranged it can be relatively easy to interrupt by attacking the caster before its animation completes. The knockdown is a very powerful feature of the spell, as it pushes targets back as well as dealing damage, so with the proper positioning it is possible to knock enemy players off of ledges.