Games Workshop has all the
FAQs you need (including for Forge World) on their main community page.
https://www.warhammer-community.com/faqs/ Just get the Imperial Armour Chaos
FAQ from that link. Sonic Dread is on the very top of page 3.
Also the
FAQs on that page now clarify that you *cannot* use warp time on a squad that has arrived from reserves. So i hate to rain on that parade... In the link provided above that is in the Rulebook
FAQ. Your plan to deep strike in a sorcerer and cast warp time on a melee unit also arriving from deep strike was considered too powerful by
GW so they took it away in April.
So here is a basic primer on "Detachments". A battle forged army just means an army made up of one or more legal "Detachments". A detachment could be anything from a Battalion (at least 2
HQ + 3 Troops), to a Vanguard (at least 1
HQ + 3 Elites), to a Supreme Command (At least 3
HQs). Each of the detachments have restrictions and they are listed in the Rule Book.
Now, Chaos and Chaos Daemons are "Battle Brothers". Which means that you can take a detachment of Chaos Marines and a Detachment of Chaos Daemons in a battle forged army. For instance, an example Daemon Detachment would be a Herald of Slaanesh, a Keeper of Secrets, and 3x 10 Daemonettes. that is a Battalion Detachment. Etc. You would need the Daemon Codex to field this detachment, and you would get access to those special rules and stratagems. What you cannot do, is mix units within a detachment. For instance, you cannot have a Chaos Marines detachment that uses a Herald of Slaanesh as an
HQ, but as long as they are in different Detachments you are good to go. Most events put a limit on the maximum number of detachments you can field (typically 3), but in theory a battle forged army can consist of as many legal detachments as you can fit together provided they are battle brothers. The Chaos Battle Brothers are; Chaos Space Marines, Thousand Sons, Death Guard, Chaos Daemons, Renegade Knights, and Renegades and Heretics (traitor guard).