"Ox", the Axeman OR "Doorman", Brutal Assassin

"Ox" was born when one of my players needed an enemy to fight.
The story (a solo-adventure) was going rather slowly; in order for the plot to progress what really needed to happen was a good fight.
And so, ASSASSINS!
While it may seem random, it had been in the works for a while. But, the specifics had been up in the air until the moment Ox arrived, stepping through a dimension door to cleave a poor terrified clerical assistant in half.
Ox is one of the Bloody Blades, an assassin of awesome skill, and ill repute, The man is a genius, as strong as a giant, and tough enough to take a hit or two. Better yet, he is a mage, a wizard of no small skill, and a master of abjurations of all kinds.
"Ox" goes by a different nickname among the other assassins.
They call him "Doorman", for he bears an axe with a powerful enchantment. It can not only cut those around him, but also space itself. His axe allows him to slice dimension doors open, at will. Effectively, it gives him use of dimension door as an SLA. This allows him to step through, kill, and step away again, before anyone can even respond.
"Doorman" often works with "Flicker", another assassin, and an equally, if differently, dangerous character.
Nobody knows Ox/Doorman's history, identity, or goals. All they know is that for now he works with the Bloody Blades, and that he is a threat to be reckoned with.

“Ox”/“Doorman” NE Human Rogue 2/Fighter 2/Wizard 4/Assassin 1/Abjurant Champion 3 CR 12

Init +3    Senses S/L +15/+15   Languages: Common, Elven, Undercommon, Ignan, Dwarven, Orc

Defenses AC 25 (+1 dex, +7 arm, +7 shld) Will +9   Ref +10   Fort +10

HP 86 (5d10+3d6+4d4+36)  

Speed 30 ft

Melee:

Greataxe +15/+10 (3d6+12+1d4 Vile/X3)

Base attack +8     grp +15

Special actions: dimension door, Sneak Attack +2d6, Death Attack (DC 16),

Special abilities: Trapfinding, evasion, poison use, abjurant armour, extended abjuration, swift abjuration

Abilities   STR 24 [20]  DEX 12  CON 16  INT 20  WIS 11  CHA 11

Feats: Able Learner, Power Attack, Cleave, Monkey Grip, Combat Casting, Dimensional Agility, Dimensional Assault, Spell Style (Flesh and Bone)

Skills: Hide +16, Move Silently +16, Knowledge (Arcana) +20, Spot +15, Listen +15, Spellcraft +20, Disguise +15, Concentration +18

Equipment: “Skeleton Key” +2 space-splitting blackfire greataxe, Belt of Giant’s Strength +4, Vest of Resistance +2, Belt of Healing

Spells (Wizard 7, Assassin 1):

Assassin DC 15+lvl

• 1 - disguise self, true strike

Wizard DC 15+lvl

• 0 - detect magic (2), prestidigitation (2)
• 1 - enlarge person, mage armour (2*), reduce person, shield (2*)
• 2 - bear’s endurance, cat’s grace, invisibility, web
• 3 - dispel magic, fly, haste
• 4 - black tentacles, lesser globe of invulnerability