Trinity of Blood (Apocalypse)

At the beginning of the Assault phase, all non-vehicle units within 12" of this formation gain Rage

Once per game: At the beginning of your opponents movement phase, declare to use this ability.

All enemy models within 24" of the formation must take a dangerous terrain test during their movement that phase. 

Flying units ( including Flying Monstrous Creatures, Flying Gargantuan Creatures and Super Heavy Fliers), Skimmers, Jump Infanty, Jet Pack Infantry and Jetbikes are not affected by this ability.