Phyrexian Seedling is a rare Creature — Phyrexian Plant card from Mystery Booster 2 (MB2), collector number 581. Current market price: $0.26, TCGplayer market prices via Scryfall.
Phyrexian Seedling enters the battlefield with a +1/+1 counter on it. Proliferatelink (Damage dealt by this creature also causes you to proliferate that many times. You proliferate before checking for lethal damage on creatures.)