If a player begins the game with a Leyline card in their opening hand, that player may begin the game with the Leyline already active on the battlefield
I am currently working with the assumtion I am dealing with 1 in 360 packs for sets starting with XY (see my post further back: Digression: What Kind of a Sequence Length to Model the XY Series?) and plan to continue using this assumption for the Sun & Moon, Sword & Shield and Scarlet & Violet Series
Selvala, Heart of the Wilds Hailing from the multiplayer-focused set Conspiracy: Take the Crown, Selvala, Heart of the Wilds is a mana engine of immense potential
You can take out something awesome and then only have to face a 3/3 vanilla token
Fiend Piece Golem Level 5 DARK Fiend Effect Monster ATK/ 2100 DEF/ 0 You can only use the 1st, 2nd, and 3rd effect of this card's name each once per turn
Give that permanent or player another counter of that kind