Ontological argument is synonymous with Tawhid argument.

[Soccer]

If there was a possible world that can exist without God, then another god can exist without God (in a particular possible world for example).

The converse of that (hence equivalent in truth statement):

If no other god can exist without God, then no possible world can exist without God.

I just thought I would point this out so that Muslims don't shoot down the ontological argument just because we didn't clarify it and Anselm and Descartes did.

The ontological argument is Tawhid but just stated differently.