CONTAINS SOME SPOILERS BUT YOU COULD PRETTY MUCH WRITE THIS SORT OF THING FOR YOURSELF
Even by the standards of flogging a franchise well past the point of its natural death, this sequel to a prequel to a spinoff to a sequel to a remake is boneheaded twaddle of a fairly mediocre order. The continuing adventures of former King Mathayus as no longer played by The Rock, it's shot in Thailand, which looks very nice but weren't they originally based in Egypt? The first Scorpion King movie may have been little more than backstory for a supporting character in The Mummy Returns, but it was enjoyably trashy, full-blown popcorn nonsense. The Scorpion King: Rise Of A Warrior was less interesting, and now here's a panache-free continuation that's continuing the trend of plummeting quality.
In The Scorpion King 3: Battle For Redemption, Mathayus (now played by Victor Webster) is no longer a king but a cynical mercenary hired by good king Ron Perlman to defend his trusted ally, neighbouring king Temuera Morrison from evil king (and Perlman's brother) Billy Zane. Morrison has  a beautiful daughter whom Zane has kidnapped, and  the fabled Book Of The Dead (which looks to have no more than twelve thick cardboard pages). If Zane gets hold of the Book, he can bring undead warriors back to life to do his bidding and take over the world, bwahahaha. Hilarity ensues.
Much of this is closer in tone to something like Xena: Warrior Princess than the first Scorpion King (or indeed Stephen Sommers' The Mummy, starting point for the whole franchise and a film which I admit I rather enjoyed). Perhaps surprisingly for its lenient 12 certificate, there's a goodly amount of hot scantily-armoured babe ass-kicking and a climactic babe-on-babe swordfight which probably counts as "something for the dads" while the mums can gaze in awe at the numerous immaculately sculpted manchests on display. It's also closer to the spirit of those terrible Roger Corman Sorceress films that came out in the wake of the original Conan.
Sadly this is barely on the level of Red Sonja. It's also a curiously ethnically diverse film: it's shot in Thailand by a Dutch director (Roel Reine, who also did Death Race 2 and the upcoming not-very-eagerly-anticipated Death Race 3); Mathyas is nominally Egyptian, his lumbering comedy sidekick is German, the love interest Asian, Zane is Unspecified Generic Villainy, and two of his zombie warriors are Japanese and Zulu. Oh, and there's a bunch of ninjas in it as well. I didn't catch any Portuguese, Afrikaans or Welsh in there but maybe they're in the deleted scenes.
Maybe I'm just being unduly harsh? This is plainly not a film to be taken overly seriously, and picking holes in it is like picking holes in Carry On Up The Jungle. On the other hand, you're still charging me money for the privilege of watching it and mediocrity cannot be excused on the grounds that it's just a lark. The Scorpion King 3 is another of those films that falls into the category of "not terrible, but just not much good". Watchable, but more than a little bit stupid.