Hi there! Cryx has decent warjacks, but they're quite vulnerable, and Cryx casters generally prefer to keep their focus to themselves. With that said:
Nightwretch / Deathripper: These bonejacks are essentially very fast arc nodes, that let you get out the trademark Cryx debuffs from a safe distance. Stopping them before they're in range is very hard.
Stalker: Even more vulnerable than the other two--but if your opponent knows how good it is at assassination, they'll focus their entire army on stopping it. Both Skarres synergise well with it, either giving it a
STR bonus that makes it even more horrific on assassination, or in immunising it from attack for a turn.
Reaper / Malic: Drag can be a hard ability to set up, but it can be decisive when you do pull it off. With Malice, you pay a bit more for a degree of self-fuelling.
Leviathan: It's a good all-rounder, though it can be rather hungry for focus to do everything it wants to.
Deathjack: It's awesome.
When you expand beyond Mangled Metal, and if you want to run multiple jacks, then Aiakos (the Cryx journeyman warcaster) and the Warwitch Siren can both relieve the focus pressure. The Siren is probably one of the best 2pt solos in the game, and Aiakos can handle a Reaper or Leviathan well enough. A Skarlock Thrall is also an excellent purchase for nearly every Cryx caster. Skarre-1 actually likes infantry more, given how her feat can turn even mediocre models into engines of destruction (and she needs fodder for Ritual Sacrifice), while Skarre-2 is more focused around delivering a few elite models into the enemy lines for two turns of doing whatever they want. Though un-targetable Bile Thralls are the stuff of nightmares for many lists.
Lastly, if you like Skarre-1 and you like pirates, there is a theme force ("Ships in the Night" that lets her run Mercenary Privateer units and treat them as Cryx models (so they benefit from her feat), alongside Revenant Crew and Ghost Raiders, as well as giving access to some amphibious Mercenary warjacks. It was published in No Quarter, but can also be found in the Forces of Distinction supplement.