Misleading Signpost

Reselecting which player or permanent a creature is attacking doesn't cause "whenever this creature attacks" abilities to trigger.

You may cast Misleading Signpost outside of a declare attackers step. If Misleading Signpost enters the battlefield outside of a declare attackers step, its ability simply doesn't trigger.

If an ability targets something controlled by the "defending player" of an attacking creature and the defending player for that creature changes before that ability resolves, the ability won't resolve because its target has become illegal.