Leyline of Vitality

The runt of the cycle, and the one that exposes what the free-on-turn-zero gimmick is actually worth. The other Leylines traffic in hard hate or hard ramp: protection, recursion denial, mana acceleration. This one offers a +0/+1 anthem and an optional point of lifegain per creature, effects so incremental that paying four mana for them would never happen. The whole pitch is the opening-hand clause: cards that do this little only justify their slot by skipping the cost entirely, arriving before turn one so the toughness boost is live for the first attack and the lifegain triggers from the first creature you cast. A free anthem that nudges every body out of one-toughness sweeper range and slowly drains a life total back up is meaningful texture on a wide creature board; the same enchantment cast off the top, as a four-mana do-nothing, is unplayable. So the card lives or dies on a mulligan call: keep it in your opener and it is a free permanent, draw it later and it is dead weight. That binary, worthless or free depending on the draw step, is the most interesting thing about an otherwise modest green enchantment, and it is the reason the Leyline mechanic favors effects this passive over effects you would actually want to hard-cast. Power that has to be free is power you accept being small.