Move Effects question - Shell Trap

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# Counters a physical move used against the user this round, with an explosion.
# (Shell Trap)
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class PokeBattle_Move_214 < PokeBattle_Move
def pbAddTarget(targets,attacker)
if attacker.effects[PBEffects::ShellTrap]>=0 &&
attacker.pbIsOpposing?(attacker.effects[PBEffects::ShellTrap])
if !attacker.pbAddTarget(targets,@battle.battlers[attacker.effects[PBEffects::ShellTrap]])
attacker.pbRandomTarget(targets)
end
end
end
def pbEffect(attacker,opponent,hitnum=0,alltargets=nil,showanimation=true)
if attacker.effects[PBEffects::Counter]<=0 || !opponent
@battle.pbDisplay(_INTL("Shell Trap failed!"))
return -1
end
ret=pbEffectFixedDamage(150,attacker,opponent,hitnum,alltargets,showanimation)
return ret
end
end