Hi all. I'm seeking advice playing my first ever real game of 40k vs a more veteran friend this weekend. His list includes over a battalion and patrol :

Epidimius, Poxbringer, Spoilpox Scrivener, Demon Prince

3 x 3 Nurglings

28 plague bearers, 29 plague bearers

7 beasts of nurgle

3 soul grinders

My list is an all comers list with

Tigurius

Chapter master w seal of oath

5 x infiltrators, 5x intercessors, 7 x intercessors

Chief apothecary w vox espiritum

5 x bladeguard vets

5 x aggressor with boltstorm gauntlets

Redemptor dread with plasma incinerator

Invictor w incendiary cannon

Invictor with iron hail autocannon

5 x eradicator w heavy melta rifle

3 x eliminator with bolt snipers

Sorry for the formatting.

Im looking for tactical advice, specifically: what to use my Seal of Oath on (Demon Prince?) and what to prioritise damage wise. Should I drop the eliminators or do you think they will do a job vs his threat multipliers? Should I focus bringing back Aggressors over Bladeguard or Eradicators vs a horde list with the Chief Apothecary?

My plan was to aggressively place the invictors and Infiltrators, redeploying with the strat if needed but ideally my warsuits could cripple a plague bearer blob from their concealed positions. My castle should hold the center of the board.

I also have 3 x assault centurions,fifteen intercessors, five more infiltrators, a lieutenant, three more eliminators and a bike chaplain could incorporate into the list.

Any and all feedback appreciated.

Cheers!