knight titans what about the new spam? grav stars, serpents, riptides, and wraith knights? what are your answers to these Mcnasties?
Knights are easy - AV13/12 vehicles are something you gotta deal with if you want to be any good at the game, and a Knight is simply an AV13 vehicle with more hull points. If you can kill a Necron vehicle, you can kill a Knight (and if you can't kill a Necron vehicle, you might want to reconsider your list).
Grav Stars, can't say I've faced one. Something with a high strength low AP weapon that can scoot around Draigo to kill all the Centurions, or a Culexus Assassin to stop them getting powers off.
Wave Serpents aren't a thing anymore.
Riptides come in two flavours, with Drones or without. With Drones, you just kill the Drones and let it run off the table. Without Drones, or if it doesn't run away, you kill it with Plasma Guns, Grav Guns, Power Fists/Thunder Hammers, Psychic Shriek or whatever else you generally use to kill 2+ save dudes. Note the Riptide isn't Fearless, so you can totally run it down in combat. Terrify also works wonders.
Wraithknights, Grav Cannons with Grav Amps seems the reliable way to do it for me. Other armies have their own good counters (Voidreaper relic, Warscythe Lychguard and Furious Charge Flayed Ones if you're feeling sassy for Necrons, Warp Spiders or Wraith-guys for Eldar, basically the whole Harlequin army, Thunderwolf Cav for Space Wolves, Monster Hunter HYMP for Tau etc. etc.