I have to do Jagd Dolls as well. For start of third leg I usually have a HT and ID prepped off of Manipulator. I can usually finish CT combo then life surge a FT, (dolls have just popped as Im using FT) Spine shatter to doll, use 4th, HT, Gierk, CT combo 4th, FT combo 4th, feed. You will start to find the optimal rotation to get the dolls down. I usually do one CT combo and one FT combo with 2 OGCDs (Legsweep & SS) and 1 ID to prep when I get back to leg.
Here is the math on the dolls. They do ~24k dmg at 100% health and 12k dmg at 50% health, 4.8k dmg at 20% health, 2.4k dmg at 10% health... you can see the math there right? Try to keep health under 15%