What's the best encounter to grind for red borders in vow?

[final locust]

Trying for Submission and Forbearance

[fiery trellis]

submission drops mainly from first encounter i think? I farmed a lot of rhulk and caretaker and didnt get any submissions... but they both good for forebearance

[final locust]

Ty! I was thinking rhulk for forbearance, but when grinding for the exotic he was just dropping armor and the glaive for me LOL