Turntimber Basilisk

If Turntimber Basilisk's landfall ability triggers multiple times during the same turn, you can have multiple creatures block it that turn if able.

Tapped creatures, creatures that can't block as the result of an effect, creatures with unpaid costs to block (such as those from War Cadence), and creatures that aren't controlled by the defending player are exempt from effects that would require them to block. Such creatures can be targeted by Turntimber Basilisk's landfall ability, but the requirement to block does nothing.

Deciding to have the targeted creature block doesn't force you to attack with Turntimber Basilisk that turn. If Turntimber Basilisk doesn't attack, the targeted creature is free to block whichever creature its controller chooses, or block no creatures at all.