Ydwen Efreet [Arabian Nights] Halfling Horror Whenever another Elf enters the

Whenever another Elf enters the battlefield under your control

you may pay 0 rather than pay the mana cost for a spell you cast with converted mana cost X or less

but I can sense some kind of comparable power in this droplet of ancient amber

Set: Urza's Saga Type: Enchantment Rarity: Rare Cost: {2}{G}{G} Sacrifice a creature: Draw cards equal to the sacrificed creature's power

Ydwen Efreet [Arabian Nights] Halfling Horror Whenever another Elf enters theSet: Arabian Nights Type: Creature Efreet Rarity: Rare Cost: {R}{R}{R} Whenever Ydwen Efreet blocks, flip a coin. If you lose the flip, remove Ydwen Efreet from combat and it can't block this turn. Creatures it was blocking that had become blocked by only Ydwen Efreet this combat become unblocked.