Leyline of the Guildpact

If Leyline of the Guildpact 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.

Murders at Karlov Manor

Murders at Karlov Manor Promos

A player’s “opening hand” is the hand of cards the player has after all players have taken mulligans. If players have any cards in hand that allow actions to be taken with them from a player’s opening hand, the starting player takes all such actions first in any order, followed by each other player in turn order. Then the first turn begins.

Each land you control will have the land types Plains, Island, Swamp, Mountain, and Forest. They’ll also have the mana ability of each basic land type (for example, Forests have “{T}: Add {G}.”). They’ll still have their other subtypes and abilities.

Giving a land additional basic land types doesn’t change its name or whether it’s legendary or basic.