If I do a combo for Taskmaster of :s: j. 
, :u: TAC to Jill, Double Knee Drop, Raven Spike xx Aegis Counter, Charging Star :s: j. :d: TAC to Jill j. :h:, the damages before Jill comes in are normal, but then when Jill shows up, her incoming hit does 49,200 damage and the j. :h: does 43,200 damage. The base damage for an incoming TAC hit is 50,000 and j. :h: is 65,000, and they scale by .9 and .85 respectively. So, the incoming TAC hit should do 32,800 damage, and the j. :h: should do 28,800 damage. If I only do the combo starting from the Raven Spike, it scales normally from the point of the DHC. If I replace the :d: TAC with a side TAC, the incoming TAC hit does 49,200 damage again, but the j. :h: does 54,000 damage. On an :u: TAC, the j. :h: does 64,800 damage. Adding a j. :s: after the j. :h: gives 38,400/45,900/57,700 instead of 38,400.
So, there is definitely some weird interaction between TACs and the DHC reset. Those numbers don’t even correspond to a damage you could get by having a certain number of hits, but are actually directly 50% higher, as if doing the TAC gives you a 50% damage boost. The side TAC gave a 87.5% boost, and the :u: TAC gives a 125% boost. Then it seems as if the boost degrades, going to 0%/20%/50% on the j. :s:. It could probably use some more research with a larger sample size.
EDIT: If I :u: TAC again as soon as Jill comes in, her TAC attack does 79,700 damage, compared to the normal 53,100, but then the incoming character (Zero in this case) does not get a damage boost on his incoming TAC attack or following attacks (j. in this case).
Even more crazy, if I start with Taskmaster, :u: TAC to Zero, :u: TAC to Jill, then do the rest of the combo, the j. :h: on an :u: TAC does 97,300 damage, and Zero gets a boost if I double :u: TAC to him, doing 38,900 instead of 25,900 on a j. .
If I start with side TAC to Zero, :u: TAC to Jill instead, Zero’s j. does 32,400 at the end.
Slash ~ st:h: xx