You can try this one:
--Werewolf - Alpha
local s,id=GetID()
function s.initial_effect(c)
--atkup
local e1=Effect.CreateEffect(c)
e1:SetType(EFFECT_TYPE_SINGLE)
e1:SetProperty(EFFECT_FLAG_SINGLE_RANGE)
e1:SetCode(EFFECT_UPDATE_ATTACK)
e1:SetRange(LOCATION_MZONE)
e1:SetValue(s.atkval)
c:RegisterEffect(e1)
--cannot be battle target
local e2=Effect.CreateEffect(c)
e2:SetType(EFFECT_TYPE_FIELD)
e2:SetCode(EFFECT_CANNOT_SELECT_BATTLE_TARGET)
e2:SetRange(LOCATION_MZONE)
e2:SetTargetRange(0,LOCATION_MZONE)
e2:SetValue(s.bttg)
c:RegisterEffect(e2)
end
function s.atkfilter(c)
return c:IsFaceup() and c:IsRace(RACE_BEASTWARRIOR)
end
function s.atkval(e,c)
return Duel.GetMatchingGroupCount(s.atkfilter,e:GetHandlerPlayer(),LOCATION_MZONE,0,nil)*300
end
function s.bttg(e,c)
return c~=e:GetHandler() and c:IsFaceup() and c:IsRace(RACE_BEASTWARRIOR)
end