Diviner's Portent

The trick here is that the two variables never fight each other. A big X on a draw spell usually means an empty hand, which is exactly the state that punishes any effect keyed off cards in hand; here, pouring mana into X does nothing to your roll one way or the other, because the d20 modifier reads your hand at resolution, not what you paid. The 15-plus band adds Scry X on top of the draw, so the payoff for a full grip is not just insurance against a bad roll but a genuine upgrade: you sculpt the next X cards before you take them. That makes the card most valuable in exactly the shell that can least afford to tap out for it, the loaded-hand deck that wants to refill and keep sculpting rather than the topdeck-mode deck that most needs raw cards. The dice mechanic invites a reading as pure variance, but the number in your hand is the lever a pilot actually controls, and it quietly rewards holding cards over emptying them. As a design it belongs to the strand of blue draw that ties the payoff to a board or hand state you built toward, rather than the flat X-for-X of something like Stroke of Genius: the same mana can buy the same cards, but only the prepared hand buys the scry alongside them.