Rulings powered by The Netrep API. If your opponent controls only 1 monster and you activate 'Soul Exchange', selecting that 1 monster as the target, after resolving 'Soul Exchange' you can Tribute that 1 monster to Tribute Summon 'Evil Hero Malicious Edge' (You would not need to Tribute an additional monster).
Duelist Pack 6: Jaden Yuki 3
If your opponent controls a monster, you can Normal Summon this card with 1 Tribute. During battle between this attacking card and a Defense Position monster whose DEF is lower than the ATK of this card, inflict the difference as Battle Damage to your opponent.
Evil Hero Malicious Edge