Ok we have all seen the new spartan abilities
From what it appears the ground pound was powered by a thruster pack like in the halo 4 intro when they thrust and gently touch down but in halo 5 it is not so gentle so maybe it will change based on fall distance so long fall,damage/kill or maybe emp close players with the cost of giving yourself a personal emp and mobility debuff, this would also explain the sliding and big jump at the start
I like it. I was wondering where they were going after showing John use them a couple times. Interesting addition, I think.