The Matrix of Time is a common Plane — Gallifrey card from Doctor Who (WHO), collector number 589. Current market price: $0.34, TCGplayer market prices via Scryfall.
When you planeswalk to The Matrix of Time, each player exiles the top card of their library. During your turn, you may play lands and cast spells from among cards exiled with The Matrix of Time. Whenever you play a land or cast a spell from among cards exiled with The Matrix of Time, that card's owner loses 3 life and exiles the top card of their library. Whenever chaos ensues, create two Treasure tokens.