When creating your card file you choose 5 cards to be soul cards and which order to play them in (the spots are labeled 1-5 with 1 being the first to go off, 5 the last). You yourself only have 1 lp but each of your soul cards has its own lp that your opponent has to get through to get to you, and every time one of your soul cards lp is reduced to 0 its soul skill (if any) goes off.
So for example I have 5 soul cards, in my first slot is a unit with lp2 and soul skill "choose a unit to get +10 attack". The first time my opponent hits me nothing happens, the soul card just goes down to 1/2 lp. The second time he hits me however the soul skill goes off and I choose a unit to get +10 attack. This continues on until all my soul cards have 0 lp. If they hit me one more time after that I lose.
The bunnies of Lavato have special abilities, like 'Action Skill: Make Carrot Disappear.'