Tribute Shield

{{CardTable
 * attribute = Trap
 * typest = Continuous
 * lore = If you control no Tribute Summoned monsters: Target 1 Level 4 or lower monster you control; it cannot be destroyed by battle or by card effects. If you would Tribute Summon a monster: You must use the target as a Tribute. When you Tribute Summon a monster using the target as a Tribute: Destroy this card.)}