To reek means to stink or smell unpleasantly while havoc means violence, destruction, devastation and mayhem. Therefore, the phrase 'reeking havoc' is inappropriate and incorrect to be utilized in writings.
Confusions might have aroused from a mistake in articulation of the phrase 'wreaking havoc'.To wreak means to inflict, cause, disseminate chaos, vengeance or some kind of damage to someone or something. Havoc, on the other hand means destruction, devastation and mayhem. We can see that both words are agreeable.
"Hulk was just wreaking havoc on everything that angered him."