The Parse Cro is a main stay in any trial group with incredibly high damage potential. There are a few tweaks you will want to consider depending on your group & needs.
You should consider setting up to run Huntman’s Mythic during boss fights / parsing but Velothi amulet during trash / content. This is a simple switch of corpsebuster onto helm to cover, and 1pc crit (Slimecraw) light to medium. This set up is demonstrated in the "trash pull" set up, but you could keep it as your main set up if a boss fight involves lots of cleave. Don't forget to also swap to medium slimecraw if using Velothi. Also in this set up, bear in mind the needs of your group - you may wish to drop carve or soul burst for vigor, or change the scripts for soul burst to suit your needs.
Your main source of damage is Corpseburster and your main way to trigger this is through re-casting detonating siphon as soon as you are able to. Otherwise it's a case of keep your DoTs up, Blast Bones every 3rd skill (as soon as you can recast it), venom skull as a spammable if everything else is up and you can't cast siphon or blast bones.
You may be asked to run Pestilent Colossus as an ultimate to provide Major Vulnerability. This lasts 12 seconds so it is usually used in rotation with another Cro, or this is covered by a Tank with Stonehulk / Turning Tide. You also will likely want to swap Avid Boneyard to Unnerving Boneyard in content to provide Major Breach & Minor Vulnerability to trash. Cros also will be benefitted by a DD, usually an Arc or Plar, running Morag Tong in support, to buff your poison and disease damage.
You may wish to use Cavalier's Charge instead of Class Flourish on the banner, and you may wish to drop Carve for Fire Rune. Results will be similar.
On my attached parse, I am running a less-optimal race for a StamCro (High Elf) and at the time of recording did not have Dawnbreaker on front bar as I'm lazy. I still hit 156k with this incomplete and sub optimal set up.