This is a pretty halfbaked idea, more like 1/4th baked, but a roaming/ganking hero that is an gatorman. Give him a passive that gives him additional movespeed and some sort of damage steroid while in the subway/sewer/underground to encourage gank rotations that involve using those instead of high flying across the map, and an active of the passive so that he can get the boost for a short time while above ground/stack it with the passive while below ground. Would also make for a good hero that is naturally capable when it comes to fighting midboss, similar to Dota heroes like Ursa who historically have had an easier time taking on Roshan.
As for the other three abilities, beats me, but I thought this sounded neat both mechanically and thematically.
As for the other three abilities, beats me, but I thought this sounded neat both mechanically and thematically.