The Ontological Argument for the Existence of God

[Angrboda]

As noted, a maximally great leprichaun would also be self-consistent and necessary. If all that is required for the rest to follow (number two onward) is that the entity be necessary and self-consistent, then a necessary unicorn also follows.

Not necessarily (pun intended). No contingent thing could satisfy the necessary being requirement. It comes directly from Aquinas’s Third Way. Here is how I explained the concept elsewhere:

“Either something is possible, capable of either being or not being, or it must be of necessity. Anyone can see that many things could possibly exist that do not. Meanwhile other things that could possibly exist do. Therefore the existence of any possible thing is contingent on the existence of either something else that is possible or something that is necessary. The chain of contingency linking possible things that do exist is an essentially ordered sequence for which a possible thing cannot serve as the first member. That is because if that thing were possible it might not have been and so now there would be nothing. But there is something. As such those things that are possible to exist and do so rely for their existence on something that is necessary. That something is a Necessary Being.”

If it were contingent then of course it wouldn't be necessary. These things I'm substituting are necessary by definition. There may be other leprichauns and unicorns that are contingent, but these are not. They are simply necessary by virtue of having always existed.