Thanks for the feedback up thread. Here's how my second pass at designing the monster for our upcoming adventure looks. This is just the wolf form, I'll get to the others when I have more time. As I haven't run this for my players yet, would love to hear how you think it gels together mechanically.
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Beast of Bechauex (Level 13 Solo Brute)
Large natural humanoid (shapechanger) XP 4,000
HP 612;
Bloodied 306
AC 25;
Fortitude 26;
Reflex25;
Will 24
Speed 8;
Initiative +11
Perception +13, low-light vision
Immune charm, polymorph
Resist 10 non-silver/blessed weapons
Vulnerable 15 criticals from silver/blessed weapons
Saving Throws +5;
Action Points 1 (see skinchanging)
TRAITS
Blood Moon (Aura 5)
The Beast pinpoints invisible or hidden foes within his aura. The Beast and allies in his aura gain +2 attack and +5 damage against bloodied enemies.
Fierce Predator
The Beast treats immobilized as slowed, stunned as dazed, and when dazed can take opportunity and immediate actions.
Magic Wolfskin
Melee weapons that are not silver or blessed shatter after striking the Beast. If the weapon is magic it instead becomes useless until it is repaired.
Wolfpack Tactics (wolf form)
When the Beast hits a creature granting combat advantage, he knocks it prone. When he hits a prone creature he deals +2d10 damage.
STANDARD ACTIONS
Vicious Bite (wolf form) * At-Will
Attack:Melee 1; +18 vs AC
Hit: 3d10+10 damage and target contracts Moon Frenzy. Crit 40+2d10 damage and 15 ongoing damage (save ends) as Beast tears at their throat.
Cold Iron Great Axe (weapon) * At-Will
Attack: Melee 2; +18 vs AC
Hit: 3d12+10 damage. Crit 46+2d12+3d6 damage, or against fey 46+2d12+3d10 damage and immobilized (save ends).
Fury of the Wolf (wolf form)
Effect: The Beast makes two basic attacks and an ally in his aura makes one.
MINOR ACTIONS
Bloodcurdling Howl (fear, wolf form) * Recharge skinchanging
Attack: Close Burst 10 (all enemies); +16 vs Will
Hit: Cannot spend healing surges and suffer disadvantaged Perception checks until end of the Beast's next turn.
Effect: Summon 4 dire wolf minions at edge of burst.
Change Shape (polymorph) * At-Will
Effect: So long as he has his magic wolfskin, the Beast can alter his form to appear as a giant wolf or a man-wolf hybrid. This stat block assumes his hybrid form.
TRIGGERED ACTIONS
Takedown (wolf form) * At-Will
Trigger: When an enemy moves to flank the Beast or knocks him prone
Attack (Immediate Reaction): +16 vs Reflex
Hit: 2d10+10 damage, knocked prone, and the Beast can slide target to any unoccupied square adjacent to him.
Jaws of the Wolf (wolf form) * At-Will
Requirements: The Beast must be bloodied.
Trigger: When an enemy within 2 squares falls prone.
Effect (Free): The Beast shifts adjacent and makes a Vicious Bite against them. If the target attempts to stand while the Beast is adjacent, they provoke an opportunity attack from the Beast.
Skinchanging (polymorph) * Encounter
Trigger: When reduced to 460 HP
Effect (No Action): The Beast shakes off all conditions, shifts 2 squares, recharges and uses Bloodcrudling Howl as a free action, then assumes Werebear Form. His stats stay the same except that he loses all traits/powers with (wolf form) keyword and instead gains those with the (bear form) keyword. The same applies when he assumes Wereboar Form. When the Beast changes forms he gains an action point (and loses his action point from his last form if unspent).
Dark Will of the Wolfskin (polymorph) * At-Will
Trigger: When reduced to 0 HP by an attack lacking (silver) or (blessed)
Effect (No Action): The Beast assumes either of his alternate forms, regaining that any HP, but no action points. Alternately, he regains 154 HP.
Skills Acrobatics +16, Aletics +18, Insight +13, Intimidate +13, Stealth +13
Str 21 (+11), Con 21 (+11), Dex 21 (+11), Int 13 (+7), Wis 14 (+8), Cha 15 (+8)
Alignment chaotic evil
Languages Common, speak with wolves
Equipment magic wolfskin, cold iron greataxe +3