502.40c.

The spell has the characteristics of the main spell, plus the text boxes of each of the spliced cards. The spell doesn't gain any other characteristics (name, mana cost, color, supertypes, card types, subtypes, etc.) of the spliced cards. Text copied onto the spell that refers to a card by name refers to the spell on the stack, not the card from which the text was copied.

Example: Glacial Ray is a red card with splice onto Arcane that reads, "Glacial Ray deals 2 damage to target creature or player." Suppose Glacial Ray is spliced onto Reach Through Mists, a blue spell. The spell is still blue, and Reach Through Mists deals the damage. This means that the ability can target a creature with protection from red and deal 2 damage to that creature.