Choose any target. Scry 3, then reveal the top card of your library. Riddle of Lightning deals damage equal to that card’s mana value to that permanent or player.
If the chosen target is an illegal target by the time Riddle of Lightning tries to resolve, the spell doesn't resolve. You don't scry 3 or reveal any card.
19-03-2021
wotc
If a card in a player's library has {X} in its mana cost, X is considered to be 0.
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.