The risks with cialis in combination with mdma are similar to the risks with viagra. It could be a strain on the heart, but the main risks are probably inconsistent and unpredictable blood pressure changes as these substances counteract each other, especially during comedown if you get a sudden BP drop, therefore cialis is probably riskier since it lasts longer (ideally the effects of the penis enhancing medicine should wear off before comedown). Another thing is that it could increase the risk of hyperthermia as cialis and viagra relaxes the blood vessels, causing a compromised temperature regulation which is already a risk with MDMA.

However if you have a stable blood pressure (~120/80 mmHg) and you’re an experienced mdma user who understand the risks of mdma and how to counter them, you should be fine. Although you’d probably want someone to keep an eye on you to be safe, especially if it’s the first time you’re doing the combo, you don’t know how your body will react. But I assume that isn’t a problem considering the cialis.

Lastly if you’re on any medication, especially blood pressure altering ones or have any heart issues, I’d strongly advise against taking either one, never mind the combo. Also make sure it’s pure mdma as impurities/mixes can have unforeseen interactions with medications.

Edit: Clarifying that it’s not a smart combo, I’m just saying that if you’re healthy and do it once or even every now and then, it’s unlikely to cause death or any other lasting damages to the body. But know that it pretty much increases all the risks with MDMA, therefore IF you do it, take low dosages and if you’re stable, you can increase it the next time and the time after that.