Lier, Disciple of the Drowned is a mythic Legendary Creature — Human Wizard card from Secret Lair Drop (SLD), collector number 2350. Current market price: $3.89 (foil $4.66), TCGplayer market prices via Scryfall.
Spells can't be countered. Each instant and sorcery card in your graveyard has flashback. The flashback cost is equal to that card's mana cost.