Valkyrie's Sword

When Valkyrie's Sword enters, you may pay {4}{W}. If you do, create a 4/4 white Angel Warrior creature token with flying and vigilance, then attach Valkyrie's Sword to it.
Equipped creature gets +2/+1.
Equip {3}

Foundations Jumpstart

Kaldheim

The Angel Warrior creature token enters the battlefield as a 4/4 creature. Any abilities that trigger when a creature with a certain power or toughness enters the battlefield will see the token enter as a 4/4 creature.

You decide whether to pay {4}{W} as the enters-the-battlefield ability resolves. If you do, you immediately create the Angel Warrior creature token and attach Valkyrie's Sword to it. No players may respond to your decision to pay or not, and no player may take actions during this process.