Explanation: Within the SCP multiverse, there's a concept called Pataphysics. It's essentially the understanding of their multiverse within the context of itself as a fictional narrative. The SCP multiverse is essentially structured like turtles all the way down but with fictional universes, and every fictional universe within the SCP canon is also its own real universe.

The SCP Foundation is able to enter and interact with the fictional universes that exist within their universe. For example, with SCP-2614 they're able to enter the Sopranos universe, and from there they can enter more meta-fictional universes that keep going down. However, universes can also interact with "higher" fictional universes. SCP-1304 is essentially a way for a fictional character to be sent into a universe "above" it, and SCP-2747 is an entity that erases fictional universes from existence before moving "up" the chain.

Since the SCP Foundation is aware that they are created by writers, they created a last-result contingency plan to kill the writers if they deem their reality may be destroyed otherwise. This is detailed in S Andrew Swann's SCP-001, in which Protocol ZK-001-Alpha is a protocol to send memetic kill agents to the higher universe.

Now, this obviously wouldn't work IRL, since memetic kill agents aren't real and the SCP Foundation can't literally kill a real person. However, Death Battle is itself a nested fictional universe. Wiz and Boomstick are fictional characters, and the fights in DB are a "lower" level of fiction. Since it has been shown that Wiz and Boomstick can interact with objects from the fictional worlds they cover, it stands to reason that they could be killed by memetic kill agents.

Funniest possible wincon ngl