They were bonuses to hit on WS/BS I believe +1/-0, +2/-1, +3/-2 bonus to penalty. Which I personally would love to see come back.
Though I'm gonna be honest Stygies and Metallica look to be the best options this round of forgeworlds. Stygies a better defensive option for backfield, Metallica for offense.
To be honest, Stygies does compete with Lucius for best defensive forge world.
-1 to hit is more effective than +1 save in most cases, but since you need to get out there and survive on an objective until next round to score, staying >12" or >18" is often not an option. The second effect for Stygies only comes into play when charging, so there is not that much synergy.
+1 save for anything that's not multi damage means considerably more resilience in CC (where most units don't have multidamage weaponry), against chaff fire (no one will target skitarii with multidamage), and will make taking wounds off vehicles with buckets of dice even less effective than it already is. If AAAC remained as is, this would mean 2+sv for basic skitarii holding an objective. +3" range is not bad, but not that much change for most weaponry either. Though 21" radium/plasma Vanguard does sound fun.
I guess that Lucius will be my new default, unless Mars' canticles and Cawl turn that around. Might even be fun to drown the board in Skitarii bodies.