Sounds awesome! I think having Elliot join would add a great dynamic to proceeding boss battles, and I'm very eager to see what you have planned for his meeting with Balbazak.
And as a matter of fact Elliot is indeed finished for the most part. Dan first produced artwork of Elliot in mid 2016 and it was awesome, but we revisited the project again in 2017 and he took it to the next level! He designed a helmet-wearing and non-helmet-wearing variant (identical sprites effectively, bar for the inclusion of exclusion of his helmet), so there's that too.
I'll get Elliot cleaned up and posted ASAP.