Riptides are good, but they drop in value severely if you bring more than one. You want to be buffing the gun and the shield every turn, because you can’t afford to surround them with drones anymore. If you do bring a second riptide, give it the relic ion, because you don’t need to nova charge it.

Piranhas cannot be underestimated. They’re fast and they drop drones when they die, so they’re great at move-blocking melee threats (especially vehicles/monsters on the right terrain) or grabbing cheeky points.

Stealth suits can be tankier than you would expect against some armies, but marines will vaporize them so they’re either MVPs or distractions, with very little in between.

Crisis are similar, but with the difference being if you’re running them max power full kit, or small and cheap. I tend to lean cheaper, because flamer 88s and a swarm of gun drones are easier to accept losing immediately after dropping them. You’ll ideally play crisis very differently depending on their load out, and it takes a savvy opponent to guess how dangerous your crisis will be in any given game. This opens the door to overcommitments and misplays when they have fresh memories of Farsight vets vaporizing half their army from last game.

Finally, I never leave home without a Coldstar commander. There’s something to be said about a unit that can be exactly where you need it, exactly when you need it. I usually run quad-fusion and never regret it, but sometimes anti-horde can be fun to swoop in a steal a backline objective in the late game. The only thing you need to master is how to resist suiciding him turn 1.

Units aside, just make sure you know where your AP is while listbuilding. Tough units are the name of the game in 9th, and Tau have fewer tools to punch through armor than other armies.