I'm the GM. My group's next move will be going into Drezen. Jestak is one of the character in the AP listed as a possible redemption character. I know anyone can be.
At best the party will be level 8 tier 2 by the time they encounter her. She is level 10.
Assuming they sway her to their side and she fully joins them, based on her stats she can potentially outshine the party in combat. Even more so in my case as I am tweaking her some.
Taking things one step further, if someone takes leadership and wants a cohort, let's assume they choose her.
Typically cohorts are roughly 2 levels behind the person with the feat. How would you all handle this in Jestak's case? Not level her anymore until the PCs are 3 levels ahead of her? Such as when they reach level 13? That seems a long time.
By the way, this is the group I'm running for:
A Paladin of Iomedae
A Druid
A Wizard who does a lot of summoning
A Kensai Magus
The Paladin is the only real heavy hitter in combat. Because unless I'm really missing something the summoned creatures aren't doing a whole lot numbers wise. The Druid is kind of a mixed bag.
With last night's adventure, I've started letting them have Sosiel as a tag along in order to help cover healing.
As she is not mythic she is about equivalent in power to a pc and will start to fall behnind which is fine in an ally. I would let her level 1 or 2 levels behind the party , for the current adventure she could either be unavailable due to injuries/delay in trusting her or you could increase the strength of opponents .
Also use a less tweaked version of her stats if she defects , the only pc she could outshine is the Paladin and Mythic Paladins are killers in this campaign so she won't as he can smite a lot and move to full attack with a better AC than her so it should be ok.
My experience is that Summoned creatures really start to become useless in Wrath around this point as they cannot keep up with the mythic power and are relatively weaker than normal. Wizards do best with utility and support magics, Save or sucks are good until the ability to spend mythic points to ignore conditions become available to the bad guys