The Mirari Conjecture

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Return target instant card from your graveyard to your hand.
II — Return target sorcery card from your graveyard to your hand.
III — Until end of turn, whenever you cast an instant or sorcery spell, copy it. You may choose new targets for the copy.

Sprite Dragon

Flying, haste
Whenever you cast a noncreature spell, put a +1/+1 counter on Sprite Dragon.

Goblin Electromancer

Instant and sorcery spells you cast cost {1} less to cast.

Shock

Crackling Drake

Flying
Crackling Drake's power is equal to the total number of instant and sorcery cards you own in exile and in your graveyard.
When Crackling Drake enters, draw a card.

Pondering Mage

When Pondering Mage enters, look at the top three cards of your library, then put them back in any order. You may shuffle. Draw a card.

Enigma Drake

Flying
Enigma Drake's power is equal to the number of instant and sorcery cards in your graveyard.

Niv-Mizzet, Parun

This spell can't be countered.
Flying
Whenever you draw a card, Niv-Mizzet, Parun deals 1 damage to any target.
Whenever a player casts an instant or sorcery spell, you draw a card.

Dive Down

Target creature you control gets +0/+3 and gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)

Frantic Inventory

Draw a card, then draw cards equal to the number of cards named Frantic Inventory in your graveyard.

The Royal Scions

+1: Draw a card, then discard a card.
+1: Target creature gets +2/+0 and gains first strike and trample until end of turn.
−8: Draw four cards. When you do, The Royal Scions deals damage to any target equal to the number of cards in your hand.

Gelectrode

{T}: Gelectrode deals 1 damage to any target.
Whenever you cast an instant or sorcery spell, you may untap Gelectrode.

Stormwing Entity

This spell costs {2}{U} less to cast if you've cast an instant or sorcery spell this turn.
Flying
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
When Stormwing Entity enters, scry 2.