The bugbear is smart enough to sneak behind the party, but he ambushes the weak looking guy (the mage) instead of taking advantage of the situation to try and kill the big guy with armor and sword (that looks like the real treat to the bugbear).
Of course this is strange unless the bugbear knows for sure that the weak looking guy (the wizard) actually is a magic user.
Of course this is strange unless the bugbear knows for sure that the weak looking guy (the wizard) actually is a magic user.