Soul Kiss

The whole point sits in the cap. Most pump auras of this vintage either gave a flat, permanent boost or, in the case of firebreathing effects, opened the floodgates so a creature could grow as large as mana allowed. Bounding the activation at three uses per turn does something both: the enchanted creature can grow, but only to a ceiling the defender can calculate. That predictability is the design, not a limitation of it. The life cost is the second lever pulling the same direction: in a color that has always sold power back for life, taxing each +2/+2 a single point means the boost is never quite free even when black mana is sitting open. Both costs together keep the aura from becoming the kind of all-in firebreathing engine that turns one untapped creature into a lethal surprise. What you get instead is a repeatable, controllable beater that swings for a known maximum, which is precisely what the per-turn ceiling was written to guarantee. As an Aura, it inherits the structural risk of its type: it leaves nothing behind if the host dies, and a single removal spell answers two cards. It belongs to black's early-set tradition of incremental, self-taxing aggression, the era before flat efficiency took over the color's threats and removal alike.