dont forget that observation haki have a passif who is 30/100 of the full power wo consum really low spirit energy and that will regenerate faster than chakra beause when in one piece there is fight they all use it during the whole fight or some use it in burst i dont know (like use it the last moment their hit connect) and ypi can implement for garp the use of tekkai while fighting he is at the peak of rokushiki so use him as a master level or more :)
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