To beat last epic boss, just concentrate on mana pool, get as much max mana as possible 5-6 waves before the last wave, then just gather mana. You should have a lot of mana to do the tactic Icewall42 said.
If your versing an epic boss, then remember to max armor skill, and keep using mana pool and fill it up so even if epic boss passes, it won't destroy all your mana. Having lots of towers with grade 4-6 gems with trenches surrounding is very hard to get past. Don't forget your arsenal of gem bombs too, and use shortcuts. (For faster attacking and reloading and combining and creating etc.)
this game is good just get pure gem masterie and fill up the last thing in upgrades it helps a ton if u already have 4 lvl 6 gems availible from the start
what you guys have said, is, I think, only a little bit of a whole. Together you have the larger picture, but I have a few things to add.
I have beaten both the 1st and 2nd epic battles, first try, with mana pools of 1000 - 2500.
1. The first thing I have to add is that you shouldn't underestimate the power of gem bombs, in the first few waves, they can be very powerful
2. When I killed the epic bosses, both of them came close to the end, but nether of them lapped once, so you don't have to use that strategy to kill them
3. Another thing to note is when the epic bosses have low life, bomb them with your high lvl gems in your towers, they kill the boss off
4. I never really have a order for my gems in towers, but I tend to put the blue and cyan gems at the start
5. Depending on your level, create pure or dual gems, don't make tripe gems. If you have dual gem mastery then fill it up and make dual gems
6. If your using the armor ability, then try a earlier level without it and put the xp points elsewhere
7. I have noticed, when playing that if you combine gems one way, say red on blue, that the stats are different then blue on red, this is untested so don't let it effect your game
8. Use trenches, and block up one area, this helps against all types of bugs (monsters)
9. Go back and replay earlier battles to boost your level, just a bit more
10. Get those amulets, they are a HUGE boost, and can, make a big difference
remember choose the correct skill to upgrade. dun worry to try, you can reset your skill point anytime.
later in the game, you may discover choice of gem color is important. try to limit the gem color to 2. Gems with more than 2 colors will be less powerful.
i prefer 2 colors more than 1 color, with the pro of ability combinations.
