New high score for Warzone in default mode: Wave 71 Score 20197
To kill the tanks use multiple Cannons and make a narrow path for them to travel. Flax Cannon needs to be upgraded all the way and 2 Flax Cannons would be better. The hardest thing to do is upgrading all the Cannons. I think I'm going to try adding more Cannons instead of up grading them fully. That last upgrade is costly.