New Champion Ghost concept

I have a really good idea for a champion who is kind of a ghost. He looks pretty spooky and is all black and shadowy and stuff. Id not really have his design fleshed out but i know what his abilities will be.

P- Undeath Whenever he dies, this champion stays alive for 7 more seconds and can move around, and has no mana costs.

Q- Echoing Screams the souls of the tormented fly in a circle around the champion, damaging anyone around him but taking a lot of mana. If an enemy is killed by this, it does not cost mana for the next 3 seconds.

W- Gates to the underworld When this ability is toggled on, this champions basic attacks are replaced with delayed small explosions that do a small amount of damage. this sucks up mana very fast.

E- Chains of death Connect two pieces of terrain within a reasonable distance with ethereal chains, that heavily damage and slow enemies that pass through them.

R- Reminder of Death All enemy champions are given a mark. After an enemy champion has a mark for 5 seconds, a large amount of damage is dealt to them. (Only way to get rid of mark is dying)

If you like this, tell me in the comments. Any criticism is appreciated.