PoE Cast On Critical Strike, Shadow, Physical builds

Hi all, POB here: Trickster peepee brand is feeling really good, a little bit squishy but not enough to make me sad. Still feels plenty beefy in non-uber content. I have a VERY specific question: I've linked Assasin's Mark to CoC, but find that I have one more gem slot that could be linked (currently just running cold snap). Any suggestions for what to plug in here? I don't care if it is a support or another skill to cast. Ideally I would like it to be something that either helps me feel tankier or helps with clear. My knowled

PoB: This build uses Kinetic Blast to Cast on Crit Dark Pact + Chain. I threw this together since I got a minion life relic and always collect CoC poison gear for fun to try stuff. The idea is that KB might sometimes look like a real CoC skill if you chain it off a Tornado. We create Tornadoes and skeletons using Poet's Pen. This build slapped way harder than I expected when I equipped it, so I thought I'd share. I'm wearing literal random gear. The core of the build can be considered poet's pen + watcher's eye + rings.

I am planning to league start a CoC build this league, having never played one before. Bit of a personal challenge and a project to work towards. With the help of some of the people on here, I got a lot of information on how CoC works and I've read up on the breakpoints. Now with the new PoB, I need to actually plan out the tree and skills. Initially I thought about doing Martyr of Innocence Blazing Salvo build, but that would require to path all the way to the templar side of the tree. So for now the plan is cold conversion Reap. However, after a bit of planning the damage and defenses are

Level 90 PoB (I use community edition): I'm using ball lightning in a couple places - the main one is in a CoC setup with blade flurry, and also a low level one in my helm with GMP, high-level added chaos, and CwDT. This procs all the time because of the herald of thunder and storm secret ring. I have another CwDT setup with blade vortex and power charge on crit for reliable power charges. That one also triggers immortal cry. I've stacked a bunch of life and ES gained on attack/spell hit, so I'm basically unkillable outside of one-shots. Aspect of the spider i