The submitted list is a fairly good assassination list already. Have the devil dogs pronto up the buccaneer, have the buccaneer walk up and throw a net at the opposing caster with a jack marshal boost to hit knocking them down, let Sylys assist Ashlynn on a gallows to draw in the caster to a better position, hit the target with hunter’s mark from Lanyssa, then charge in a fully loaded Rocianante for free and watch the opposition go splat.

The list falls short vs. hordes or high armor though, so a few changes to round it out may be in order. I like Sylys a lot, but maybe not at 15 points. He’s a really good solo but at 15 points you need a little offense out of every point you can get it from. Likewise, I also feel the devil dogs and buccaneer are a little too narrow in their goals and don’t necessarily fit well at 15 points. They die too easy to be relied on as a front line. Unlike Andy however, I really like Rocianante with Ashlynn. That +2 def vs melee and defenseive strike with the pow 17 reach makes meleeing her down an unfavorable proposal. His good range, good rat, and aoe also make him undeniably a better shooter than the rover and he’ll fit perfectly hanging back by Ashlynn’s side. Lanyssa can be a huge asset with hunter’s mark if the rest of your list can capitalize on it so she could be either in or out. I would try taking the list in a direction more like this:
Ashlynn d’Elyse (*6pts)
* Rocinante (9pts)
Horgenhold Forge Guard (Leader and 9 Grunts) (8pts)
Gorman di Wulfe, Rogue Alchemist (2pts)
Lanyssa Ryssyll, Nyss Sorceress (2pts)

The forge guard are a great front line unit that can lay a beating on almost any heavy and get so much from the quicken spell and hunter’s mark They will still die but your opponent will have to put more effort into it and with the full unit you may have more infantry than he has attacks. Gorman is an amazing solo in general but in this list he makes a fair substitution for the buccaneer with black oil rather than the net as your ranged defense-lowering tool. He will have to play farther back than the buccaneer but he has plenty of tools to shine in that role as well. This variation of the Ashlynn list is built more for a slugfest than assassination. Removing enemy threats before your forces are exhausted and using quickdraw and admonition to stay away from assassinations will be the keys to victory.