When can players take back decisions or actions in competitive play, and what are the requirements for rewinding actions? We are now in Radiance and from my understanding there's been an update. All similar questions are from before Vendetta.

It depends on the event's OPL — and the framework is unchanged. The current Radiance-era Tournament Rules (2026-10-09) carry the same two mechanisms as the Vendetta version: a player reversing their own decision (TR 509) and a judge rewinding the game state (TR 701.5). Nothing in the Radiance patch notes or errata touches either, so pre-Vendetta answers describing this structure are still accurate.

Player take-backs (TR 509). At Casual (low) OPL you can reverse your most recent action and decide differently — including not doing it at all — as long as neither player has taken a new action since, and the change doesn't have to be immediate (509.3). At Competitive/Professional (high) OPL it's much tighter: only immediately after, and only for three things — choices just made and communicated for putting a spell or ability on the chain, where you played a unit or gear, or a choice like which unit to move or what to discard (509.4). In either case you can ready runes you just exhausted or unrecycle runes you just recycled for that decision, provided no new action has happened and focus hasn't been passed (509.5).

Two hard stops: you can't reverse once your opponent has revealed information showing the decision was a tactical error (509.6 — the Wuju Bladesman example), and reversing to fish for information, or in reaction to an opponent's physical tell or them starting a game action, is angle shooting (509.7). Once an action is communicated to an opponent it generally can't be taken back (509.2).

Judge rewinds (TR 701.5) are a remedy for a game error, not a take-back tool. A simple rewind covers only the last completed action or one in progress — any judge may do it, it rewinds to before the action began (e.g. before the card would be put on the chain), and runes paid are readied/unrecycled. Anything more complex needs the head judge, or designated appeals judges at high OPL; it reverses each intervening action most-recent-first in correct sequence, chooses a random card where the identity of a card was non-public, and shuffles learned-but-not-drawn cards back into the randomized portion of the deck.