Evermind

(Nonexistent mana costs can't be paid.)
Draw a card.
Splice onto Arcane {1}{U} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

The List

Saviors of Kamigawa

(Spells without mana costs can't be played.)
Draw a card.
Evermind is blue.
Splice onto Arcane {1}{U} (As you play an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Evermind is a blue Arcane instant card. Cards that check whether a card has any of those attributes will affect Evermind. For example, you can exile it (as a blue card) to pay the alternative costs of spells like Force of Will and Disrupting Shoal (X = 0). You could search for it with Mystical Tutor because it's an instant or Eerie Procession because it's an Arcane spell.

Evermind has no mana cost, which means it can't normally be cast as a spell. You could, however, cast it via some alternate means, like with Sunforger or Kaho, Minamo Historian.

If a spell or effect, such as Parallectric Feedback, asks for Evermind's mana value, it's 0.

A card with a splice ability can't be spliced onto itself because the spell is on the stack (and not in your hand) when you reveal the cards you want to splice onto it.

Although originally printed with a characteristic-defining ability that defined its color, this card now has a color indicator. This color indicator can't be affected by text-changing effects (such as the one created by Crystal Spray), although color-changing effects can still overwrite it.

If all of the spell's targets are illegal when the spell tries to resolve, it won't resolve and none of its effects will happen.

You choose all targets for the spell after revealing cards you want to splice, including any targets required by the text of any of those cards. You may choose a different target for each instance of the word "target" on the resulting spell.

You reveal all cards you intend to splice at the same time. Each individual card can be spliced only once onto any one spell.

A card with no mana cost can't be cast normally; you'll need a way to cast it for an alternative cost or without paying its mana cost, such as by suspending it.

If a card with no mana cost is given an alternative cost equal to its mana cost (by Snapcaster Mage, for example), that cost cannot be paid and the card cannot be cast this way.