Complex sentence: The pinnacle of her skills is the Creation Rebirth and its derived technique, the Strength of a Hundred Technique, which she taught to her disciple Sakura and use mitotic regeneration to make them nearly unkillable in battle.
Split into simpler sentences: The pinnacle of her skills is the Creation Rebirth and its derived technique, the Strength of a Hundred Technique, which she taught to her disciple Sakura. Both Tsunade and Sakura use mitotic regeneration to make them nearly unkillable in battle.