Rule evolution
Rule 509.1g
Earliest archived Rules release: 2009-10-01 · 0 wording revisions · 0 renumberings
Earliest archived Rules release509.1gDetails
Each chosen creature still controlled by the defending player becomes a blocking creature. Each one is blocking the attacking creatures chosen for it. It remains a blocking creature until it's removed from combat or the combat phase ends, whichever comes first. See rule 506.4.