Windshaper Planetar

Reselecting which player or planeswalker a creature is attacking ignores all requirements, restrictions, and costs associated with attacking.

If you reselect which player or planeswalker an attacking creature is attacking, that creature is still considered to have attacked the player or planeswalker as declared, but it is now attacking the new player or planeswalker.

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