Sounds good, just a few nitpicks
The old
WH40k in 30 minutes rules had a sum of 33 as limit, which is actually surprisingly well chosen. A chimeras or razorback at those point levels aren't game breaking, wave serpents or dreadnoughts are. It also disallowed models with more than three wounds, you might want to look into that as well.
Engages an enemy warlord in challenge-1
You lose experience from fighting the warlord? I should assume that it's the other way around. If the warlord then kills the unit they already lose point for that. Also, tarpitting a death star is good play, it shouldn't be punished.
Refuses a challenge -1
Winning challenges already gives a huge bonus (which is great), but this punishes units with functional characters, like apothecaries, pain boyz or librarians, which aren't meant to fight in challenges. Again, you are punishing good play. If you really want to make turning down challenges unattractive, give one point to whoever is issuing the challenge when his opponent is chickening out.
4- gains one stat of choice
5- increase IN, LD, Wound (to a max of +2)
6- increase BS, WS, Strength by 1 (to a max of +2)
4 can also increase toughness and attacks, while the others can't. Is this on purpose? Limit at 2 is good.
IMHO distributing all stats across the three and allowing one pick rolls would work a lot better. Additional stats are very powerful, I wouldn't hand out three at once - any unit of troops getting either 5 or 6 would turn into a mad killing machine rivaling most elite choices of their codices. Now think about a unit of nob bikers, paladins, screamers or a seer council rolling a single 5 - they will probably proceed to crush the entire campaign.
If an enemy warlord is killed, roll for damage trait.
1- commander loses 1 reward and unavailable 1 match
2- unavalible 1 match
3- loses 1 reward
Note that warlords tend to get killed in games more often than not, and it's already a big hit to your game. While I can get behind the warlord not being allowed for one game, taking away rewards seems harsh, considering that he already got less rewards because he got killed and he might have to sit out a game on top of that. How about instead halving his movement (limp leg), having him start at half his wounds, rounded down next game to display he hasn't healed fully yet, or disallowing the use of a second hand (can't use 2-handed or second melee weapon, heavy weapons or storm shields) because of a broken arm. Punishing people for getting their commander taken out is alright, but taking away hard earned rewards is going to cause frustration.
4- re roll
Boring
4- Fog = range of all shootin attack reduced by 4 inches (never less than 10)
You could save yourself some rule issues by just counting it as night fighting - similar effect, less headaches.
5- Tremors = run and assault rolls reduced by 1
Tremors usually make all terrain count as difficult terrain in
40k. That said, assault doesn't really need another kick in the teeth, maybe also reduce all
BS by one because everyone's hands are shaking?
6- Storm = lightning (at end of each phase roll 1 d6 for each unit, on a 5-6, squad is hit with 1d3 str 4 pinning attacks
Add "
AP: -" for your rule lawyers