While going over an old versus thread from last year I thought what would happen if the Death Note and most of the characters of the manga existed in the DC or Marvel Universes and how would the Death Note and these characters affect either universe? Everyone is free to give their ideas and self written scenarios as how it would all play out and to make it easier I will give some conditions to prevent arguing and so people can go wild as much as they want with their scenarios.
Starting
Like in the manga Light through Ryuk acquires the Death Note and begins his killing spree and this attracts the attention of the Marvel and DC characters both villains and heroes.
Characters Present
L., Near, Mellow, Watari, and the other members of Wammy's House are absent from either universe.
Everyone else from the Death Note universe now lives in Marvel/DC.
Additional Death Note Abilities, Conditions, and Assumptions
The Death Note's powers are stronger than any other force of magic in Marvel/DC. So someone like Doctor Strange can't simply counter its powers or track Light down using magic.
Anything that is biological can be killed by it regardless of what race they are from or if they are made differently yes that means aliens, Atlanteans, Amazons even Wonder Woman can be affected by it.
Anyone who touches the Death Note is immune to mind powers (mind reading, mind control, etc).
Almost nobody in Marvel/DC knows about the shinigami or their realm prior to Light picking up the Death Note.
And like always names must be written down but they have to be in that person's native language.
And those are the conditions make sure that you follow them before writing out your scenario.