During the Main Phase (Quick Effect): You can reveal this card in your hand; banish it (face-down), and if you do, Special Summon 1 of your face-down banished "Trirealm Rift" monsters, except a Level 6 monster. You can only use this effect of "Burial Summit Trirealm Rift Helheim" once per turn. If this card is Normal or Special Summoned: Banish (face-down) the top 6 cards of your Deck. Other "Trirealm Rift" cards you control cannot be destroyed by your opponent's card effects, also your opponent cannot target them with card effects.