Tiras, Keeper of Genesis [BP01-EN029] Starfoil Rare Spirit Monster you can add 1 Counter

you can add 1 Counter Trap Card from your Graveyard to your hand

each time your opponent Special Summons a monster(s)

by Tributing 1 Thunder Effect non-Fusion Monster (in which case you do not use "Polymerization")

you can Special Summon it

Set: 2016 Mega-Tins Card type: Normal Monster Rarity: Ultra Rare Attack: 2500 Defense: 2100

Tiras, Keeper of Genesis [BP01-EN029] Starfoil Rare Spirit Monster you can add 1 CounterSet: Battle Pack: Epic Dawn Card type: Xyz Effect Monster Rarity: Starfoil Rare Attack: 2600 Defense: 1700 2 Level 5 monsters. This card's effects can only be applied or activated while it has Xyz Material. This card cannot be destroyed by card effects. At the end of the Battle Phase, if this card attacked or was attacked: Target 1 card your opponent controls, destroy the target. During each of your End Phases: Detach 1 Xyz Material from this card.