My advice is to play The Giant, since it's a smaller map and you can easily progress to the rounds faster. I also wouldn't use points all at one go. I would advise you to casually use all points over time since for me it does better than just to spend it altogether.
I think it's like 30 or more liquid div. an hour with this strategy. Just keep in mind that it destroys your score per min, and average waves per game.
Step 1: Buy the 3 round burst pistol at wave one Shadows of Evil.
Step 2: Shoot the shadow man until you advance all the way to round 15.
Step 3: buy as many doors as possible (skipping rounds gives you a little over 1,000 points per round skipped).
- Buy Juggernog if it is in a good and easy place to grab it.
- Buy the wall Kuda along the way.
- Once you open all the doors, you have a choice. Continue on like a normal game of zombies, or die and repeat. Dieing hurts your stats but gets you more div. Going on buffers your stats and you get less div.
Another thing: don't point whore in standard games. If you are on the giant, run trains and continuously pack a punch/teleport/hit the box/ refill wall weapon ammo. All of these things grant div. if you have an organized squad. Save the last zombie, let it down you, and go buy all the perks. Repeat this for all members every round. Usually get 0-1 div. per round this way.
My usual round of The Giant past round 30 consists of training in the VMP room. I then kill the train, run up, teleport, pack a punch my non-used secondary. Then I run to the box, hit the box. Train, kill zombie train. Run to closest teleport, pack a punch again, run back to VMP room, refil VMP ammo, train, kill train, teleport, pack a punch, mystery box, train, kill train, teleport, back to VMP room, refill VMP ammo, teleport, pack a punch, hit box, train, kill train, teleport, back to VMP room. Team saves last zombie, we all down to the zombie and rebuy perks, and then repeat pattern next round. Sometimes you burn points quicker than you get them. Just take a break from div farming and point farm to replenish your points again.
You want you points to be under 30,000 at all times. Always ensure you have enough points for perks and wall ammo though encase you go down.