What must a player do during the declare blockers step?

During the declare blockers step of combat, players must announce which of their creatures will block the attacking creatures. This is a critical part of the combat process because it is when the defending player has the opportunity to decide how to interact with the declared attackers. By using their creatures to block, players can strategically prevent damage from getting through to them, potentially eliminating attacking creatures or controlling the flow of combat.

Choosing which creatures attack occurs in the previous step, the declare attackers step, and assigning damage order takes place after blockers have been declared and is part of the damage assignment process. Finishing the combat phase is not an action taken during the declare blockers step; rather, it is the final stage of combat after all actions, including declaring blockers and resolving damage, have been completed. Thus, the requirement to announce blockers distinctly marks this critical moment in the combat sequence.