Causing an opponent to lose the game after you've announced that you're casting a spell with undaunted and determined its total cost won't cause you to have to pay more mana.
08-11-2016
wotc
If each target is illegal as Seeds of Renewal resolves, Seeds of Renewal doesn't resolve and is put into its owner's graveyard. It's not exiled.
08-11-2016
wotc
Effects that reduce what you pay to cast a spell don't affect its mana value.
08-11-2016
wotc
If one target becomes illegal before Seeds of Renewal resolves, you'll still return the legal target from your graveyard to your hand.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.