While you have a "Fusion Beast" family Spirit in your Trash, this set Burst is unaffected by opposing effects.
[ Burst: After Your Life Decreases] Until the next opposing Start Step, opposing Spirits are Cost 0 and have 0 Symbols. After that effect resolves, summon this card without paying the cost.
[LV2] (When Attacks) Discard 4 cards from the opposing decktop.