1600 2 CAD DE/CWE

My buddy is bringing something like this

fly Daemon Prince (nurgle most likely) also lvl 3 psyker with wings
a sorcerer
2 units of chaos marines in rhinos
a chaos knight titan
and a firebase support cadre

He may bring cultist instead of marines and I'm unsure the loadout he will take out the broadsides. He's used railsides in the past. The one limitation on the match is only two detachments.

My list:
DE
Archon with a blaster, shadowfield, armor of misery, wwp
3 squads of 5 warriors in venoms
CWE
2 faseers both with singing spears only one with the spirit stone
1 unit of 5 scythguard
2 5 man dire avengers squads in wave serpants with bright lances
wraithknight ghostglaive and dual scatter laser

my list comes out to exactly 1600

I'm hoping that by having more troops on the board I'll be able to grab objectives, while using the unit of deepstriking scythguard with farseers to eliminate the cadre of Tau and the wraithknight is on knight titan duty.

I've played against his Tau army and his Chaos army before but, not in the same list and I've never played against the Knight Titan before.

I'd try some Fire Dragons in a raider with a Farseer and an Archon+WWP... they sound like they could do a hole in that knight, specially if you deep strike in two sides of the knight at a time and aim+shoot the lance to the knight: you force him to choose which side he wants his ion shield to work, then you shoot him from another with your dragon raiders, which is a cool name, plus guide (maybe doom) and a blaster and a singing spear. He won't bring his knight again.

Or maybe it's not enough for you and you prefer wraithguard... I won't blame you, they are made for this.

Unless you're doing Psychic Shriek with your Farseers, change the armor of misery for a Helm of Spite... it'll hurt his lvl3 flying daemon prince and sorcerer, and you'll be getting close anyway.

The rest is fine I guess... depending on your playing style, and you know your enemy better anyway.