Thantis, the Warweaver is a mythic Legendary Creature — Spider card from The List (PLST), collector number C18-46. Current market price: $0.56, TCGplayer market prices via Scryfall.
Reach, vigilance All creatures attack each combat if able. Whenever a creature attacks you or a planeswalker you control, put a +1/+1 counter on Thantis.