Mythical Beast Cerberus (SD6-EN002) - Structure Deck: Spellcaster's Judgment 1st Edition

Each time you or your opponent activates 1 Spell Card, put 1 Spell Counter on this card. Increase the ATK of this card by 500 points for each Spell Counter on this card. At the end of the Battle Phase of the turn this card battles, remove all Spell Counters from this card.