I suspect much more than eight non-land, non-engine cards would be a problem but I have yet to push those limits properly and am more confident in the minimum requirements than I am with the maximum
Rishkar, Peema Renegade 6.5 Early days thus far but a pretty impressive card even if it isn't optimized in this list
With all the ETB effects in these two colors, you can draw, destroy, or shut down multiple targets with each hit
Doom Prevails (Blue/Black/Red) Doom Prevails is led by Doctor Doom, King of Latveria (with Loki, the Deceiver as the alternate commander), and brings back the Connive mechanic from Streets of New Capenna, pairing it with life-drain effects and graveyard value
This gives some flexibility to attack one place and deal damage to everybody to progress tha game, and again Hylda might like this card
With enough artifacts, this wont cost generic mana