Intervention Pact

Free in the only sense that matters at the moment you cast it: this is a prevention spell with no upfront cost, paid for entirely on credit. The whole conceit of this loan structure is the deferral, and the white member buys you a Fog-on-one-source plus lifegain now in exchange for a bill that comes due on your next upkeep, with your life on the line if it goes unpaid. That deferral is the design's entire engine. It lets a defensive play happen with no mana held up, which matters most when every point of mana is already committed elsewhere or when you simply do not have it yet and need to survive to untap. The choice is deliberately one-source, not blanket prevention: it names a specific incoming hit (a burn spell aimed at your face, an attacker's combat damage, a single ping from a damage engine) rather than a board full of threats, and the life gained scales with how big that one hit was. Note that it chooses a source rather than targeting one, so hexproof, shroud, and ward on the attacker are irrelevant. What keeps the deal honest is that the bill is not optional and not cheap; pay-or-lose is the cleanest possible expression of borrowing against the future, and a turn where you cannot spare turns your own safety net into the thing that kills you.