Cocaine and alcohol basically combine into cocaethyline which has a distinguishably differrent effect.
What always pops up first when I'm asked this question is IV cocaine, heroin and ketamine. Opioids were always awesome with cocaine.
More recently just amphetamines and a small amount of benzos. Shrooms or acid with MDMA. I once smoked plain Salvia leaves on a very small dose of shrooms and had an amazing DMT like experience.