Split is a rune effect in Magic Missile, a Signature Wizard skill projectile skill.
This rune effect fires three MM projectiles instead of just one. The three move out in a cluster, and all three may hit the same target, if it is large enough. The missiles do not spread out further as they travel, and how widely-spread they are can not be controlled by the player's targeting.
This effect is handy to hit moving or small targets, and when all three bolts hit it deals slightly more damage than Arcane Blast, the first Magic Missile.
Skill Rune Effects
Refer to the Magic Missile rune effects article for thorough descriptions of all five rune effects in this skill, including screenshots, videos, strategy tips, and other related information.
|| Magic Missile
|| This is a Signature spell. Signature spells are free to cast.|
Launch a missile of magic energy, dealing 230% weapon damage as Arcane.
|| Fire 3 missiles that each deal 80% weapon damage as Arcane.
The three missiles vary slightly in spread, but this is a random effect and not one players can modify in any way.
This was one of the rune effects most changed by the removal of runes as an item, since the number of MMs fired used to increase with each rune level, up to 8 at rune level 7, which would have been awesome against large groups of enemies. Now there are always just three, which removes any chance of this rune effect being viable in the late game.
The skill rune name was changed as well, and it was previously known as "Fork." Presumably the developers thought "Split" was more appropriate now that there are now always three bolts, while the previous system started out with two, and then increased from there, up to a maximum of 8.
Prior to the skill revision in February 2012, this rune effect was enabled by the Indigo Rune, granting the following effect with a level 7 runestone.
Fires 8 missiles that each deal 55% weapon damage as Arcane.