Halo 4 will get mapmaking support under the Forge toolkit that has long followed the series. A panel today at Rooster Teeth's RTX event in Austin, Texas revealed the new Forge's feature set.
[Update] That video above shows the toolkit in action. It's footage from the RTX panel discussion on Saturday.
A "ton of new user-friendly functionality" can be expected in Forge, write's Polygon's Griffin McElroy. Probably the biggest parameter controls described include "Player Trait Zones," which enforce traits such as run speed and jump height on any player who enters a space defined on the map. Another field can enhance or completely reverse the gravity field of an area on the map, for anyone who steps into it.
Certain Affinity, the developer of Crimson Alliance, is responsible for the new Forge mapmaking tools. The studio has created maps for the Halo series in the past.