New Death Realm Champs?

Mordekaiser's Death Realm Ult got me thinking. It'd be a shame if that alternate summoners rift had no use outside of Mordekaiser. There's a lot more that you could do with that system. This is partially for the champion's own interesting mechanics, and partially as a counter to Mordekaiser. These other champions who can access the Death Realm would be able to enter or exit his ult using their ults. I've got a few Ideas myself, but I'd like to hear what you guys think as well.

First off, an assassin who, rather than camouflage or invisibility, can dive into the death realm, gain bonus MS, and exit at a point of their choosing (Within a few seconds). Other players would be able to see their spirit in the overworld, but since their Icon doesn't come up, and it doesn't proc wards or ghost poros, map awareness wouldn't help, they'd have to notice the visual and react to it in time. This dive would leave portals others could enter and exit through, and after the duration of the ult, any champions in the Realm would take Max HP% Damage per second until they exit. Once there are no champions inside, the portals would close. Due to their MS Increase, anyone trying to follow them would have a difficult time exiting before dying, but it could be used for a quick gank, allowing your team to get to a location unharmed, like 5-man diving to steal baron. Champions like Mordekaiser who can access the death realm, could use their ult outside of it to trap them in his ults radius, or inside to pull them back out. They'd also be immune to the Damage over Time due to being able to access the death realm on their own. This realm would expand with the assasins movement, creating a tunnel along their path.

Secondly, a tank who, similar to Sion, has an after death effect. Rather than coming back as a Zombie though, they'd be a Ghost. They would respawn at the fountain immediately on death in the death realm. They'd be able to buy items during death as normal, but would be able to walk somewhere else on the map to exit the death realm when their re-spawn timer runs out. If they ran into a Death Realm ult while doing this, their respawn timer would be cut short and they'd be able to exit as one normally would in that ult. This would be his passive, and his ult would be similar to Zileans, bringing its target back as a Ghost if killed in the next few seconds, shortening their re-spawn timer for that death, and empowering them over that duration. This would allow you to, for instance, bring back your AD carry more quickly when they die defending the nexus or in pursuit of a penta. This death realm would look completely open, just like a barren summoners rift.

Now, for how they'd interact with eachother. Mordekaiser's wall would be an impassable barrier in the death realm, but if someone entered the death realm on top of it, they'd be inside the walls, turning a 1v1 into a 2v1. The assassin could lead the whole team into or out of mordekaiser's ult, as it would leave a portal they could enter or exit from. If the assassin was pulled in, they could use their ult to exit, leaving one portal and resulting in a reduced cooldown. The Tank would turn into a ghost in mordekaiser's ult if killed, still resulting in a death, but being returned to full HP and MP immediately, and would be pulled back out alive at the end of the ult. If Mordekaiser ulted on top of the Tank's Ghost, visible as a spirit in the overworld, the Tank would be trapped in the walls, and pulled out alive at the end of the duration. The Tank, walking through the death realm, would be able to access the portals the Assassin left, exiting from his re-spawn timer early. The Tank could also use his ult to pull someone out of the death realm, considering them "dead" if they're still in it when the duration ends. If well timed before mordekaiser's ult, it could pull someone out of it, wasting his ult. This would result in a reduced cooldown for the tank.

So, what are your suggestions? Do you think this would help to balance the death realm mechanic and be an interesting addition?