Stalwart Valkyrie
Creature — Angel Warrior
You may pay 
and exile a creature card from your graveyard rather than pay this spell's mana cost.
Flying
"Only the worthy may pass."
Jason Rainville
Foundations Jumpstart (J25)
• #258Rulings
Stalwart Valkyrie has mana value 4, no matter what you actually paid to cast it.
(wotc • 2021-02-05)
Once you announce that you're casting Stalwart Valkyrie using its alternative cost, no player may take other actions until the spell's been paid for. Notably, players can't try to remove creature cards from your graveyard to stop you from casting the spell.
(wotc • 2021-02-05)
Casting Stalwart Valkyrie for its alternative cost doesn't change when you can cast it.
(wotc • 2021-02-05)
Printings
Price History (USD)
Price History (EUR)
Rulings
Stalwart Valkyrie has mana value 4, no matter what you actually paid to cast it.
(wotc • 2021-02-05)
Once you announce that you're casting Stalwart Valkyrie using its alternative cost, no player may take other actions until the spell's been paid for. Notably, players can't try to remove creature cards from your graveyard to stop you from casting the spell.
(wotc • 2021-02-05)
Casting Stalwart Valkyrie for its alternative cost doesn't change when you can cast it.
(wotc • 2021-02-05)