4 Balloons and 5 Grenades at the start of the fight. They are all weak to water. After some of them are defeated, 3 more Grenades and Yerma will appear as reinforcements.
If you don't have enough damage to kill them quickly then be prepared to get hit with a lot of "Fire" spells. When the fireballs get low, they can self destruct to deal damage in a wide area.