Card name: Supernova
Splinter: Death
Attack: 0
Speed: 1
Life: 1
Shield: 0
Abilities: Debuff (can't receive any buffs), Explosion (causes 1 unavoidable magical damage to all enemies and allies and self-destructs)

I think it would create a very interesting gameplay where whoever's playing the Supernova card must avoid playing low-HP monsters and focus on spreading his attacks so that the enemy will have as many cards with 1 HP to win asap. It's a good strategy against shielded monsters and even against Divine Shield entirely.

While the enemy can easily take Supernova down with an opportunity card with more than 1 speed.