What is the common bad effects of mdma? What is the way it can cause death?

Stroke, heart attack. Mdma (ecstacy) is a stimulant that is neurotoxic - damages brain cells, impairs cognitive function, seizures, strokes. It can affect cardiovascular system, irregular heart rhythm, rapid heart rate, elevated blood pressure, heart attack.
MDMA. MDMA has many potential adverse effects to include: irritability, aggression, ^ in impulsivity, anxiety, panic attacks, depression, sleep problems, low appetite, V sex drive & pleasure, ^ blood pressure, cardiac arrythmia, ^ body temperature, muscle cramps, dehydration, chills, sweats, visual changes as well as seizures, CVA renal or heart failure. MDMA depletes brain of serotonin.