I just had this thought; in halo 5, we only have one ability on spawn, which is thruster pack or a hologram. That said there are equipment scattered around each map, and picking one up combines the use of both abilities.
Say I pick up a bubble shield and hologram is my default. I could deploy the shield now or send out my hologram, and have the hologram do it at a distance. Or maybe my default is a thruster and I pick up a grav lift. I could use the grav lift normally, or I could thruster, then immediatly grav lift mid air with the required timing.
New equipment can be made from this and to keep it from being too random, little icons or on model visual cues can be used so that the unpredictability comes from the player rather than the ability.