While I often find myself a bit of a grammar snob - and try very hard to keep it to myself - here is one typo I have seen wrong EVERY TIME on gamer forums.
Namely, causing havoc.
"Havoc" is a broad term for chaos, mayhem, mischief. To cause havoc is to make all pretense of order rain down (or up) like so much hilarious confetti. Havoc is exactly what you want to cause to any enemy, the more clever and complex their plans the better!
When talking about making havoc happen, one could saying "causing havoc" or anything along those lines. The old school way of saying something is making havoc happen is "wreaking havoc."
"To wreak" is the same meaning as "to cause" only replacing cause with wreak implies that the result leads to damage or harm (works great with havoc!)
NEVER EVER say "wrecking havoc," because that implies making havoc less havoc-y (no that's not a word) as "to wreck" is to break, or ruin. Wrecking havoc is the same as making things more orderly - which is, I hope, the last thing you would want when hoping to make havoc happen.
Do not wreck it.
All clear? Good! This has been my occasional Harrumph for the time being.