Leyline of the Guildpact is a rare Enchantment card from Murders at Karlov Manor (MKM), collector number 217. Current market price: $4.66 (foil $4.21), TCGplayer market prices via Scryfall.
If this card is in your opening hand, you may begin the game with it on the battlefield. Each nonland permanent you control is all colors. Lands you control are every basic land type in addition to their other types.