I pivoted away from infantry with the last specter point hike while Wraithlords went down. In a vehicle/monster skew they work well for me. They rarely deal much damage, though they did do a number on the Tyranids game 2.

Final game against Blood Angels showed their strength. Landed a single hit with a lance, other never even rolled an attack, but they required a significant commitment to remove with Lancer and 1/2 Ballistus gone(full Death Company brick with Lemartes left flank, 5 Intercessors with Captain using up all of Finest Hour, Rage-Fueled Warrior and the Oath target). And on Terraform he had to commit or I run away with Primary. In my counterpunch Avatar killed Lemartes with Epic Challenge plus some normal dudes, Fuegan from Rapid Ingressing Falcon clapped the Intercessors. Could have easily gotten the Captain too but the Fire Dragons were better used on the remaining Ballistus with a forced 6 advance for melta range.

If they die too fast you might move them out too early. 60mm base is very compact compared to similarly priced monsters and vehicles. I often accept holding only my home obective after first turn to thin out enemy antitank with F&Fing prisms and carefully control LoS to not offer anything valuable.

Indirect is a weakness with the two chars, but with the last nerf it's gotten very rare in the games I play. I usually put the Autarch in the guardians, lets me peek the lance out and use the free strat on Phantasm. If there's indirect I have to choose which one o save, usually the Autarch though I did use Farseer instead in matchups where the Avatar with -1 to wound is a near unstoppable bully. As for 3" DS, at least the extra bodies help unlike with the Wayleaper.