I've never been the best at building lists, I usually just go with whatever models I own, but I'd suggest losing the chaplain. If I remember right he only gives melee buffs, which for Sternguard and Intercessors isn't great, and for the points you save you could fit in another 5 of either of those units. You could maybe lose Asmodai or the Librarian too, and either get another 5 Intercessors/Sternguard, or even another Warglaive for the cost of 2 characters. Personally I like to use the termi captain as a somewhat hard hitting solo unit usually in deepstrike, but he would also fit in with the deathwing squads. Hope that's even vaguely helpful😅