503. Upkeep Step
In short
Das Versorgungssegment (Upkeep): Sammelpunkt für „zu Beginn deines Versorgungssegments"-Trigger und das erste Zeitfenster im Zug, in dem gewirkt werden kann. Klassischer Ort für Fragen wie „kann ich noch reagieren, bevor …?" — ja, hier.
Informal summary — the official English text below is authoritative.
503.1.The upkeep step has no turn-based actions. Once it begins, the active player gets priority. (See rule 117, “Timing and Priority.”)
503.2.If a spell states that it may be cast only “after [a player’s] upkeep step,” and the turn has multiple upkeep steps, that spell may be cast any time after the first upkeep step ends.
Source: Wizards of the Coast, Magic: The Gathering Comprehensive Rules. Unofficial presentation under the Fan Content Policy. Rules effective as of Aug 7, 2026