Ach, All ye young whippasnappas be forgettin' about spell penetration!
MotW/Kings provide 35 Resistance in all magic schools, aside from holy. Races with resistances gain one point of resistance per level, at 70, 70 resistance works out to be approximately 28.57%, In either arcane, (Gnome/Blood elf) Nature, (Night elf/Tauren/Worgen) Frost, (Dwarf) Shadow, (Undead/Draenei/Worgen). Worgen has both nature and shadow resistance, Slightly less then other races, with their one specific resistance.
The 35 Spell penetration to cloak enchant would cover the resistance granted by Motw/Kings, But depending on class/spec, 'Capping' it at 70 generally tends to be the way to go, At least as far as non-frost mages, Seeing as some people out there are getting 300-500 frost resistance, Just to deal with the mages in the bracket.
Ach! All ye fine dandies prancin' about with yer 'quipment full-o intellect!
Past thought; Ugh. Sorry if the % of resistance is @ 70. Memory fails me this time of.. Er, day.