Balduvian Warlord's ability may be activated during any player's turn.

The targeted creature that's removed from combat may then block the attacking creature that it was originally blocking. If so, that creature will no longer be unblocked.

If an attacking creature becomes unblocked this way and remains unblocked, it will deal its combat damage to the defending player. Abilities that say "When this creature attacks and isn't blocked" won't trigger.

If the targeted creature has a "When this creature blocks" ability, it will trigger when Balduvian Warlord's ability resolves and the creature blocks again.

If an attacking creature has an ability that triggers "When this creature becomes blocked," it triggers when a creature blocks it due to the Warlord's ability only if it was unblocked at that point.

If an attacking creature has a "When this creature becomes blocked by [a creature]" ability, it triggers when a creature blocks it due to the Warlord's ability.

The attacking creature will become unblocked only if the targeted creature was the only one that blocked it this combat, even if all the other creatures that were blocking it are no longer on the battlefield or are no longer blocking it (even those removed with other Balduvian Warlords' abilities).