The backbone of the Stygian Royal Army, 3 regiments of shielded pike. Heavy infantry with long spears forming a solid wall in defense and an unstoppable tide on the offensive!
Eventually these guys will be backed up by bowmen and slingers, as well as lighter armed foot spear.
The cavalry arm will get several regiments of Guard Lancers and some medium and light horse as well.
I have used Xyston 'Egyptian Marines" from their Persian range.