If MDMA reduces the chances of fearful reactions, the code-word is chances. Don't fully rely on something like MDMA to get you through the momentary terrors of something like DMT or 5-MeO-DMT. Don't get me wrong, I think they are fabulous, but they can be more white-knuckled than 10x the hardest rollercoaster. If you wanna take these, just accept that going in or just skip them altogether.
Even stronger put: you should probably never take on anything because you'd like something else like a drug to carry the burden for you. If you take those odds, always accept the possibility that you have to carry the weight yourself, with some possible whiplash from - in this case - synergy from a MDMA reinforced trip, not going euphorically.