It was fairly well known since the game was played here, so I don’t mind hitting on a few points.
Every game is different, but I was very fortunate to get a great start and a huge blood economy going. The mobility of your cheap flying units, and ability to mass them and swarm indies (can recruit them in caves and forests), helped me get a good jump early. A few mages were changed later and made more costly and harder to recruit (added temples as necessary, I believe), but they are still in a good place. Early game even throwing out a few Summon Imp spells in battle could turn the tide as needed. Just fly some blood hunters with slaves in tow to where you need a bit more punch or defense.
Late game a combination of free spawn beast bats from Onaqui, summoned Ozelotl (blessed triple attack flyers), Darkness cast by the Onaqui, and other assorted blood summons and battlefield spells like Leech and Arch Devils and it was tough to beat late mid game with all armies able to fly and jump all over. I didn’t even bother trying to go for the Balam or Chaac and never needed them.
EDIT: Also, that new Blood Surge bless looks especially nice for them, imho. Ozelotl with that bless would be downright mean.