I played against Ossiarch 1k list today. My list was a fun one, and my opponents probably wasn't best either and, on top of that, it was his first two games. But he is a 40k player so got a grasp of it fast enough.
I brought Slann, Skink Priest, 20 skinks, Oldblood on Carnosaur and Bastiladon. He proxied Boneshaper, Soulmason, 2x20 mortek guard and Harvester.
Some observations:
- just as I expected, they are really slow. They need their RDP to move units and if they do so, they cannot reroll saves or get rend on spears. Even with that - 7 inches is not that much;
- they crumble to rend and mortal wounds. Stellar tempest and razordons did a nice job at bringing them down. And 3 models restored per hero phase is not that mad actually.
We are going to test 2k game and I'll go for Thunderquake. It think, it is really perfect battalion for seraphon to counter Ossiarch. Ossiarch doesn't have too much bodies and bastiladons and razordons kill them pretty quickly+mortal wounds from engine of gods and astrolith gives +1 to casts for stellar tempest (the best spell to kill mortek guard).