warrior stack??? with change class?

[jimmys7777]

first of all sry for my poor english.. :)

so i kick door and is a 13lvl monster
i am warrioir elvf/halfing
and i have combat level 12
if in combat "with brerseking" change elf and halfing to ork and dwarf so (cobat level 12+2(from the played card)=14 and then change class from warrioir to theaf and then finish the monster

i lose 12>13 ? , i win with 14>13 or 15>13 ????
if i change class the playd cards brom brerserking is stil working ????