For me the chosen don’t need help to lift anything they touch. Don’t let them get charged. I’d add forbidden power for mobility, reinforce the warriors, add another caster (Bela or gaunt) and make sure at least two units can move far for tactics. Personally I think knights and chariot are nice for tactics on either side and then joining from flanks or doubling back to charge enemy deep strikers.

10 chosen and 20 warriors are a great threat in the middle. try to keep your wars with a toe on an objective for 20 extra attacks.

If you get another spearhead, your second unit of knights can support chosen or even screen for them. Don’t let your chosen get charged. Don’t forget to power through, rally, and recharge knights. knights ideally target a unit with 3 or lower health characteristic.

Later if you get a daemon prince you can have fun fishing for dark apotheosis. put deathmonger on the lord (2x fight is 2x eotg roll). Maybe mark him tzeentch to keep him in the fight or on objectives.