Well I'm pretty sure you guys know to NEVER use the wowlauncher and always wow.exe when it comes to cheating.
In cheatengine or any other disassembler and debugger, parts of damage can be edited. MaxHealth and regular health, if all of those addresses are set to 0, you don't take fall damage and you don't lose the ability to breathe when under water.
Back to health, if you find out what accesses it, while you're damaged and healing, you should get a few flds, ucomiss, movss. If you nop one of the flds, your health, not maxhealth should change to -1.# K earlier I managed to fully get infinite health using this somehow.
See what you can do