You can Tribute Summon this card face-up by Tributing 1 Beast-Warrior monster. If this card battles a monster, any battle damage it inflicts to your opponent is doubled. If a Beast-Warrior monster(s) is Normal or Special Summoned to your field while this card is in your GY (except during the Damage Step): You can add this card to your hand, then immediately after this effect resolves, you can Tribute Summon this card face-up, and if you do, it gains 500 ATK, also banish it when it leaves the field. You can only use this effect of "Assault Lion" once per turn.