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StarLadder tournaments are for good teams with top equipment. There is no 'M' limit, however most Star Ladder matches have a certain format, such as only Hornet and Railgun, and most commonly light format: Hunters, Hornets, Wasps, Rails, and one Smoky (which can only be used on Hornet or Wasp). In all Star Ladder matches there is nothing preventing participants from using M3s, and there are no handicaps. So it is rare to see M2s or M1s used in Star Ladder, as this will put you at a disadvantge to your opponents. But Star Ladder is not strictly only for M3s.