In fact, if you want more XP, I recommend TRYING to lose levels as quick as possible, killing as close to 50% as possible. You get only about 15% more xp for finishing (and those are bonuses)
The amount of xp you get it set for each level, and then you get a percentage of it. THAT MEANS- On level 16 it is 60k, just put in one or two towers, kill 50% of the enemies and lose the level. If you have the +25% xp you get 45k xp in 60 seconds.
Also could be worthwhile to take out the "clicking" necessary to pick up gold and mana potions. The coins get stuck under scroll spells, then you have to click through 3 scroll spells to get the +50/+100 gold coins that are on the ground. I don't like wasting those scrolls :)
Get rid of the random troops losing 50% health. Give us the ability to dismiss troops. Change the random generation of troops that pop up. My first 14 troops in endless were riflemen and grenaiders. I don't want riflemen or grenaiders
and rockets dont even count for a combo hit unless you kill, this game has just poorly poorly made triggers, too many problems and was badly scaled with upgrades. 1/5