The overlord , 18 warriors , scarabs and stalker as a retribution phalanx , with an additional 10 warriors a cryptek and szeras and the barge . I fill my hq and troops ? I'm very confused . Been gaming for years for fantasy only .'
Ah, I see the confusion. The Retribution Phalanx is a Formation with specific unit requirements as listed in the sheet you got with the starter box. A Combined Arms Detachment has its own requirements, 1 HQ and 2 Troops, that must be different units. Units can not be selected in two different Detachment/Formations. Right now you have:
Given the way Detachments work in 8th edition this collection of models could be used in a Patrol Detachment, dropping one HQ option, or in a Battalion Detachment, adding two Warriors and playing three 10-man squads.
Unfortunately Canada got rid of the penny and now my two cents rounds down to zero, so...take it for what you will.