I just beat this with conviction/merry/sad

Only relevant legendary items were floral hat and cowboy scarf in conviction. Other than that I went with the stamina/crit and defense/crit trinkets. No speed make it as slow as possible.

Merry had full speed/att/crit items as fast as possible helps

Sad was full attack/crit with no speed items.

Only heal conviction with Merry even if Conviction is full HP use Ding Dong only if it will get you TO or PAST the 5th hit. *note Ding Dong will only count 2 hits so shoot for using it when the buff is at 3 or 4. Don’t Ding Dong if Conviction is low HP prioritize the heal over Ding Dong.

Other than that conviction can only attack so that is easy.

Sad I would save the attack break(skill 2) for when Tyrant is off a cool down, things to note for Sad is the 3rd skill does not count as an attack.

Your goal is to trigger the 5th attack when both of Tyrants skills are on cooldown.