The Spellshot turns an enemy into a Skeep for a few seconds. If the enemy is immune, the Spellshot instantly casts a free Spell on that enemy and gains two free stacks of Spellweaving.
While Polymorph is active, any player that damages the skeep has a chance to cast a free spell. This effect is guaranteed the first time the Fatemaker deals Gun Damage. If the Spellshot casts a free spell this way, they gain a stack of Spellweaving.