My most competitive deck with an 80% win ratio, when playing in my local playgroup. Often times I am seen as arch nemesis but if the counter spells and damage prevention spells are used correctly you will survive. Once Jadzi hits the battlefield and you have a cost reducer out it's time to start playing solitaire, taking extra turns, and drawing your whole deck to win while casting a slew of free spells that then trigger Jadzi again.

Currently rated 8 or 9 out of 10 for power level. To get up to 10 improvements would include removing permanents like artifacts and enchantments to make Jadzi's ability last longer. There needs to be balance though and you have to be able to find a cost reducer when needed. Remove some but not all cost reducers and win con creatures for drawing your deck, and add more instants and sorceries that can tutor for the one reducer or win con creature you need.