Tripropellant Engines

Ok so we have the nice and basic monoprop and bipropellant engines.  Now lets have the really exotic and high power tripropellant engines!  Such as the insane mixture of Hydrogen, Florine, and Lithium!  This stuff is even better than the maby pandy lox/hydrogen mix!  It has an even higher ISP for the low low cost of some of the most vicious propellants out there.  Molten lithium, fluorine which burns everything, and the molten metal lithium.  I am sure there are other equally exotic and well researched and horrifically dangerous but very good tripropellant engines.

Here is a NASA doc about some tripropellant:
ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19860018652.pdf