Cryptic Serpent
Creature — Serpent
This spell costs 
less to cast for each instant and sorcery card in your graveyard.
It slithers through the senses, constricting consciousness and poisoning perceptions.
Lius Lasahido
Jumpstart (JMP)
• #146Rulings
A split card only counts once for Cryptic Serpent's ability, even if it's both an instant and a sorcery.
(wotc • 2017-04-18)
Cryptic Serpent's ability doesn't change its mana cost or mana value. It just reduces the cost to cast the spell.
(wotc • 2017-04-18)
Cryptic Serpent's ability can't reduce its cost to less than {U}{U}.
(wotc • 2017-04-18)
Rulings
A split card only counts once for Cryptic Serpent's ability, even if it's both an instant and a sorcery.
(wotc • 2017-04-18)
Cryptic Serpent's ability doesn't change its mana cost or mana value. It just reduces the cost to cast the spell.
(wotc • 2017-04-18)
Cryptic Serpent's ability can't reduce its cost to less than {U}{U}.
(wotc • 2017-04-18)