Been trying to optimize the Adaptive Duelist + Familiar combo. Some things:
Charging Dancers stack exponentially. A conga-line of Charging Dancers to the left of the Adaptive Duelist is awesome. The left-most Dancer can be a Mirroring Dancer with no downside (all the others should/want Charging Aspect).
Adaptive Duelist scales faster if the difference between DMG and HP is "wider" so making it have very unbalanced high HP (since HP is easier to increase) makes it much, much stronger. So getting Growth onto the Duelist for several Depths, before you get Adaptive on it, is great.
Maze enemies in Endless are brutal. Having two Adaptive Duelists is a good move, and use Fractured Prospector (Fractured Aspect to let Prospector copy Familiar's combat trait).
It's best to have an Incarnator on the left-most side, then the Prospector 2nd-left most, the Dancer conga-line, two Adaptive Duelists, then a Hoarder (replaced by a Botanist every so often), so the Duelists scale even faster (not that it's needed to)