Only possible when going second as it needs to go into the Battle Phase. The idea is just to get 2 Fire monsters on field and link into Hiita. For instance if you have Sky Burn and a FK monster that special summon itself in hand (Barong, Rangbali or little Kirin) you can also use sky burn to pop Ulcanix which will end with Garunix and a FK monster on field. [learnt this combo from Umbranox]