If I find Noxus Hopeful during Void Rush can I play it for free?

To determine if you can play Noxus Hopeful for free when found via Void Rush, we must look at the cost calculation rules and the specific interactions between these two cards.

The Ruling

Yes, you can play Noxus Hopeful for [0] Energy using Void Rush, provided you meet the specific conditions for cost reduction.

Cost Calculation Breakdown

1. Base Cost: Noxus Hopeful has a base Energy cost of [4].
2. Void Rush Reduction: Void Rush allows you to play the chosen card, reducing its cost by [2].
   • Calculation: 4 (Base) - 2 (Void Rush) = [2] Energy remaining.
3. Legion Interaction: Noxus Hopeful has a [Legion] ability that reduces its cost by [2] if you have played another card earlier in the turn.
   • As established in RiftJudge FAQ #8943, playing Void Rush as the first card of the turn satisfies the [Legion] condition for the unit played from it.
   • Calculation: 2 (Remaining) - 2 (Legion) = [0] Energy.

The Critical Constraint

According to Rule 356.5, Energy and Power costs cannot be reduced below 0. While the math above results in 0 Energy, you must ensure you have the necessary resources to finalize the play.

Summary of Sequence

1. Play Void Rush: You pay the cost for Void Rush and place it on the chain. This is the first card played this turn.
2. Resolve Void Rush: You reveal the top 2 cards, choose Noxus Hopeful, and initiate the process to play it.
3. Determine Total Cost:
   • Start with the base cost of [4].
   • Apply the Void Rush reduction: [4] - [2] = [2].
   • Apply the [Legion] reduction: Because Void Rush was finalized earlier in the turn, the [Legion] condition is met. [2] - [2] = [0].
4. Finalization: You play Noxus Hopeful for [0] Energy.

Conclusion: You can play Noxus Hopeful for [0] Energy if you have already played Void Rush as your first card of the turn, satisfying the [Legion] requirement.

Note: I could not fully verify this ruling against the retrieved rules.