Erratic Portal

Bounce built around a tax rather than a hard answer, and the tax is the whole point. The activation only returns the creature if its controller declines to pay one mana, which means it almost never functions as removal: against an opponent, it is a soft tempo nudge they can shrug off for a single mana, since the is theirs to pay; against your own board, it is a trigger machine that recurs enters-the-battlefield effects on demand. That asymmetry is what keeps a colorless, repeatable bounce ability honest. It cannot reliably strip a blocker or undo a threat, because the defending player decides whether to pay, and the cost they face is trivial. What it does reliably is reset your own creatures, where the optional payment costs you nothing because you are the one choosing to bounce. The tap requirement is the other constraint: it caps the loop at one activation per turn absent an outside untap effect, favoring a single, deliberate bounce rather than a chained engine. The result reads like interaction and plays like value; the friction baked into the "unless its controller pays" clause is what redirects it from a control tool toward a recursion enabler. It stands as a clean early example of a bounce effect deliberately priced so that the targeted creature's controller, not the activator, decides whether the bounce resolves at all.