mtg wilhelt commander deck Innistrad: Midnight Hunt card Zombie Tribal Commander deck featuring Wilhelt MTG Commander Deck EDH Deck

712.3b While the two cards of a meld pair are on the battlefield as a melded permanent, the object represented by those cards has only the characteristics of the combined back face, except that its converted mana cost is the sum of the converted mana costs of its front faces

A game specifically about card advantage is one example, which it can be especially if Force of Will is a factor, but this tends to come up in spots where being green is a real cost

Enchantment Color tag templates(None) Sanguine Bond Whenever you gain life, target opponent loses that much life

Given the way these work, you can keep sending them back to each other as long as you can pay the cost