Alright, there was a request for this in the comments on the game, so here is how I beat it (always).
First, skills. Max initial and max mana, mana gain per second, mana gain per kill, cost to create and combine gems, cost to create towers and trenches, and number of initial starter gems. Also helpful is pure gem mastery and the mana save skill. Don't use dual gem mastery because you should be using dual gems at this point.
Next, towers. Only one tower can be placed by the entrance. Place it there and use that for a Purple gem. Then surround the path down to the first turn with towers and gems. Get grade 7 slow and triple damage if possible (maybe not since you are using all gems). Least important is splash, since it is slow and has little damage on the first hit. Chain hit has speed to make up for its useless skill, mana steal helps gain mana throughout, even against the epic boss. Shock, though its skill maxes early, is useful to increase the hits other can get on the boss. Poison is your best friend, especially a good level 6+.
Here is the big part you need to remember: Two high (6+ if possible, at least level 5) purple to reduce his armor level. KEEP A PURPLE GEM ATTACKING THE BOSS AT ALL TIMES!!! Once you get his armor level down to about 50 (70 levels) the hp starts falling off.
Preparing: Much mana pool. Get so it has about 11000. The monster will take 7100 to banish, and don't get your hopes up about banishing it twice. With the armor save maxed, it takes 5800 or so. Once you have that, start buying gems. I prefer to get it to the point where you have a multiplier of 2.2 for the kills, but that's just me, and I'm used to that. Anyway, start buying and maxing gems, remembering to keep two seperate purple.
Positioning: Keep the poison, triple damage, slow, armor reducers, plus any shocks attacking as much as possible. Have towers spread out around the rest of the path to keep the poison and armor attacking as much as possible to damage as long as possible.
The battle: Keep the poison and armor reducer on the boss on the first trek, and then the slow and poison on the second.The last little loop, take advantage of where your towers are already placed to get maximum damage. Get another purple up to the top. The monster should die on the second trek.
If you still cant beat it, go get glowing on all other battles and try for glowing on the hiddens (hint: mana pool really helps)
Thanks. If you still need help, I will come back and post more, including a link to a map i created to help you visualize what I am describing.
UPDATE: Alright, I just played it again (with a horrible set up to start with) and there are two spots by the spawn where you can place gems. Doesn't matter which one goes where, but I like to put a poison there as well. 2 poisons, 2 armor reducing, 2 shock if you can, and try to get a long slow, fast lime, high yellow, and, if you can afford it, keep buying gems and save them for use as gem bombs the second time around.
Personally I dont care about gem colour though. I use gems that slow and hit fast more often than not. Also, maybe make a stockpile of level 4 gems till the epic boss appears. Thats going to be my strategy, load up on high grade gems fit grade 6 or higher in towers, water trench then barrage him. I havent came to a point where my epic boss runs twice( not at this level! at lower ones)
well i use this method only because of his high level. I use triple damage because of its immense power. If it wasn't so slow it would be perfect. Get it to level 9 and it can hit 1/4 or more of the field (probably closer to 1/3, i try to get it on the hidden level) I love lime because I can get its speed well over 100, and mana steal actually has pretty good power, it just doesn't have the range that triple damage does. Then again, in most situations mana steal is a better gem. Gonna try to gembomb through the first epic battle eventually lol!!!
alright I played the yellow level. Got 158 minimum damage, 50% chance, range of 1/3 of the board, and a speed of 48. I could not get the stats to match up in that game.
Oh and gembombing the first epic battle was too easy lols
