Das in ein neues Script unter dem Original kopieren. TURNS_MAX bestimmt, wie viele Runden angezeigt werden.

Code: 
class Window_CombatLog < Window_Selectable
  TURNS_MAX = 10
  #--------------------------------------------------------------------------
  # initialize
  #--------------------------------------------------------------------------
  def initialize
    @data = []
    @turn_data = Array.new(TURNS_MAX) { [] }
    super(0, 0, Graphics.width, Graphics.height-120)
    deactivate
    hide
  end
  
  #--------------------------------------------------------------------------
  # add_line
  #--------------------------------------------------------------------------
  def add_line(text)
    return if text == "-" && current_turn.last == "-"
    current_turn.push(text)
  end
  
  #--------------------------------------------------------------------------
  # item_max
  #--------------------------------------------------------------------------
  def item_max
    @turn_data.inject(0) { |sum, i| sum += i.size }
  end
  
  def data
    @turn_data.inject(:+)
  end
  
  #--------------------------------------------------------------------------
  # draw_item
  #--------------------------------------------------------------------------
  def draw_item(index)
    text = data[index]
    return if text.nil?
    rect = item_rect_for_text(index)
    if text == "-"
      draw_horz_line(rect.y)
    else
      draw_text_ex(rect.x, rect.y, text)
    end
  end
  
  def start_turn
    @turn_data.rotate!
    current_turn.clear
  end
  
  def current_turn
    @turn_data.last
  end
end

class Scene_Battle < Scene_Base
  #--------------------------------------------------------------------------
  # alias method: turn_start
  #--------------------------------------------------------------------------
  alias scene_battle_turn_start_cld turn_start
  def turn_start
    scene_battle_turn_start_cld
    @combatlog_window.start_turn
    @combatlog_window.add_line("-")
    text = sprintf(YEA::COMBAT_LOG::TEXT_TURN_NUMBER, $game_troop.turn_count)
    @combatlog_window.add_line(text)
    @combatlog_window.add_line("-")
  end
end
Mangels installiertem Maker wie immer ungetestet :3