-Use SE on an opponent's monster
-Activate the second effect of e-con, taking control of your opponents second monster by tributing their first (which you just hit with SE).
-Perform a tribute summon using your opponents second monster.
You now have a 5* or higher monster on the field and in the process destroyed 2 of theirs.
no you cant,
1. I did SE 1 of my opponent monster
2. I activate my e-con (effect no 2)
3. I couldn't tribute my opponent monster which I already hit by SE. The game only have option to tribute my own monster instead of the SE'ed monster