Darth Tyranus was an extremely accomplished Dark Lord of the Sith and was formerly Darth Sidious' apprentice. He specialized in lightsaber dueling, though his skills in the Force were not to be ignored. You most likely remember him as Count Dooku, the general of the Separatist army. Dooku used Form II, a style that used elegant and efficient movements to redirect opponent's attacks against them. Form II was thought to be the most effective combat style against other lightsaber wielders.