>>539783840
No offence meant but you probably just played it wrong and didn't use your magic well, i've played that campaign dozens of times and would expect to handily win that with only furies lost.
Pic related, his army's stronger in campaign but so is your magic and you have teleport ambush. If you play it again get burning head asap on your cultist(also very good against the slaanesh faction near you) and don't bother attacking oxy or trying to dive the chameleon skinks with kairos.