(An ongoing scheme remains face up until it's abandoned.)
Whenever a creature attacks and isn't blocked, if you're the defending player, create a 0/1 green Plant creature token that's blocking that creature.
When four or more creatures attack you, abandon this scheme at end of combat.
(15/06/2010)
For each unblocked creature attacking you, you must put a Plant token onto the battlefield blocking it, even if you don’t want to.
(15/06/2010)
Putting a blocking creature onto the battlefield doesn’t trigger “Whenever a creature blocks” abilities. It also won’t check blocking restrictions, costs, or requirements.
(15/06/2010)
Putting a blocking creature onto the battlefield will trigger “When this creature becomes blocked by a creature” abilities. It will also trigger “When this creature becomes blocked” abilities in this case, because the attacking creature had not yet been blocked that combat.
(15/06/2010)
The Plant token blocks the attacking creature even if the block couldn’t legally be declared (for example, if the attacking creature has flying).
(15/06/2010)
You’re the defending player if a creature is attacking you or a planeswalker you control.
(15/06/2010)
The last ability triggers only if four or more creatures were declared as attackers during your opponents’ declare attackers step. Only creatures attacking you are counted; creatures attacking your planeswalkers are not. The creatures may be controlled by different players.
