Declare Assisting Blockers

• Immediately after the declare blockers action, before the active player receives priority, during the declare blockers step, players other than the defending player may, in turn order, declare assisting blockers.
• Declaring assisting blockers is a turn-based action and does not use the stack.
• To declare assisting blockers, a player may tap any number of untapped creatures they control with defender. If they do, for each creature tapped this way, they may choose any number of attacking creatures or bosses that creature could have blocked as if its controller was the defending player. Those creatures become blockers for those attacking creatures or bosses.
• A creature can be declared as an assisting blocker even if it has summing sickness.