If you play Heedless Resurrection on a Ferrous Forerunner, can you play the same Forerunner from trash?
No, you cannot use Heedless Resurrection to kill a unit and then resurrect that same unit from your trash.
According to RiftJudge FAQ #9523, this interaction is prohibited because of how targeting and costs are handled during the process of playing a card:
- Locking Targets (Step 2 of the Showdown Flow/Playing a Card): When you play Heedless Resurrection, you must choose a valid target unit from your trash before you pay any costs. At this point, your Ferrous Forerunner is still on the board and has not yet entered the trash. Therefore, it is not a valid target.
- Paying Costs (Step 4): You pay the additional cost by killing a friendly unit, moving it to the trash. Because the target was already locked in during the previous step, you cannot retroactively select the unit you just killed.
Rule References: 355.5, 355.9.a, 355.15, 357.2.