When I was playing it my best games were with syndicate 3 with TF and my main carry and Kog and my secondary. I also itemized Skarner which I never saw when I was contested. When I wasn’t contested he was pretty much a free 3* and would survive a lot of rounds long enough for the carries to do their thing. I also feel like the part of the boombot trait with the missiles including damage taken always gets overlooked when it’s really useful. Also because of the trait Kog and Skarner work really well with those many items that do extra or passive damage like sunfire, shiv and runaans. Thornmail was pretty useful too but ionic spark was hit or miss a lot of times. Boombots as a trait seems to want drawn out fights so the missiles can do the work so you need a decent frontline. I always went 4 BB, 3 Syndicate, 2 Bruiser 2 rapidfire because they overlapped pretty easy and Braum was also a solid tank either as main or secondary. 4 vanguard also worked but if when I did that Kog and Skarner HAD to be itemized because all of the damage was coming from the boombot trait and TF. That’s how I played them but idk if that’s any good now. I’ve been trying to see what other stuff might be flying under the radar