The Rockgrinder wiffed that particular game, but that was on a charge against a primaris walker (the one with the Marine in the chassy) and awful dice rolls on my part!
I adore rockgrinders, on decent rolls they can shred a ton of hard targets on a charge with minimal support. (I had a Rockgrinder in 8th grind a Chapter Master into a fine red paste in one charge, and plow through whole units of intercessors in a turn. Hilarious and fitting!)
Rockgrinders are almost always going to die, so explosive charges are a solid option overall, leaving random characters near units for support especially in tight setups makes for perfect rockgrinder charges.
As for my other big units: IMHO in this edition they are fantastic. We can very handily stop claiming of certain objectives, The acolytes are often a "one and done" kinda deal, but they hit hard *AND* are troops with Obsec which is critical this edition. The 20 man Shotgun/Grenade unit of neophytes is similar, I plan to often use "perfect ambush?" (the one where you drop 3 inches away) and feed something 36 Str 4 shotgun shells and 2 Krak Grenades from Launchers preferably on an objective. Support optional depending on how the table is setup, but the Kelermorph is good support for that unit, as he creates an Aura by killing a single model (very likely against infantry of most stripes)
The Ridge Runners and Jackal Alphus form a module that runs around, tags important tanks, and Fires 3d3 Lascannon-equiv shots into them hitting on 3+ and wounding on +1 to the wound roll.
Edited by Sonoftherubric21, 26 August 2020 - 09:30 PM.