Alright, since it appears most people are getting stuck on the Epic levels, I'll tell you an easy strategy.
When you get to any Epic level, you may want to redistribute your points. You'll want any skill that gives or saves you mana. You'll want to max out the "Lower mana cost for gem creating and combining" skill, the "More mana per kill" skill, and the "More initial and maximum mana" skill. If you have to choose between two, because you don't have enough points, the first two I mentioned are the better options. On the other hand, if you have any points left over, put them into "More mana replenish per second."
Now, if you maxed out "More initial and maximum mana," then you'll have a little over 600 mana to start with. Create a square (grade 2) gem, and put it in the tower closest to the monster's spawn point. Don't worry, a single square gem can hold off the first 3 or 4 waves by itself, as long as you don't send them out together. Don't worry about the first 31 waves, all they are is preparation for the Epic Boss on wave 32.
Next, use the mana pool spell. Add another square (grade 2) gem (with a tower if you want to keep it close to the spawn point, which isn't a bad idea, since you'll be adding towers in later) if your first is having trouble. Next, just sit and watch. Wait until you have enough mana, and then use the mana pool spell, up until you have 3,000 or more max mana. Now wait, and then replace the square gems with diamond (grade 3) gems, and add another tower if you feel you need it.
Once again, wait until you have enough mana, and then use the mana pool spell up until you have around 5,000-6,000 max mana. Now start mass producing pentagonal (grade 4) gems. Start building several more towers close to the spawn point, and putting pentagonal (grade 4) gems in them.
Alright, now, you're going to need higher grade gems. Several gems are more beneficial in Pure form than others. So try to get 1-3 of the following: a high level green gem to sap away the life, a high level purple gem to lower the ridiculously high armor level, a high level cyan gem, for the shock chance, or a high level blue gem to slow it down.
Try to keep those colors pure, but feel free to combine limes, reds, yellows, and oranges for maximum grade, and maximum mana.
Now, spend the last 5-6 waves just waiting. Don't spend any mana. Get up to at least 4,500 mana. If you get enough that you could buy, say, and extra tower, and still have 4,500 mana in your pool, feel free. Put it somewhere further along the path so that you have somewhere to transfer one of your more powerful gems to after the Boss gets out of it's range.
Once the boss comes, let your gems do all the work. Move them along the path to further towers so that the boss stays in their sights. I defeated him before he reached the end of the path, however, if he happens to get there, you have that 4,500 mana backed up to banish him back the the beginning, so rinse, and repeat. It should be no problem to have him dead by the second time around.
