I did it with Orbweaver/trick shot in 2 hours and 30 min. You score 4800 points with hero or Yao, and I did it with plenty of sigils to spare. Now I did go to T6 for the mythic bounty troop, but if you are willing to use orbs you could probably finish with t4 on Sunday with free sigils…
Ps. My Orbweaver is 100, so I saw a bunch of instant kills trigger during my run, made it faster, and I think it was the first time I saw the 7% kill thing trigger more than once in a blue moon.