I am lvl 35 and I have not gotten to the second epic yet. I did however find an easy way to get the glowing frame.
What I do is pute all my skill points in mana regeneration skills, and the gem bomb skill. I just click the enemy wave bar to the left and keep clicking it so that each one slides (best way to get points is to send out a wave early).
After I do this about 7 times, untill enemys start creeping out of their base or untill the game gets laggy, I make as many lvl 1 gems as possible and bomb the enemies. As I bomb them I watch my mana pool and I create more many as soon as I get the chance. When I run out of gems, I make more lvl 1 gems. It is strongly recomended taht you go ahead and press Ctrl + Click. You will gain mana much much faster than you'll lose it.
By the time you get to the harder to kill enemies, or the faster ones, you should have enough mana for some higher lvl gems to finish them off more quickly. Lvl 2-3 gems generally work well enough.
You can usualy finish off early bosses with lvl 1s and 2s. By the time you get the harder to kill bosses, you should be able to make lvl 5 and 6 gems. Both finish them off fairly easily.
This strategy does not work on epic bosses, You do regain mana very quickly but not enough to survive an epic attack. This strategy is not recomended on the hidden lvls either. I have not gotten to the 2nd epic yet, so I do not know if this strategy will work throughout the game but so far I have glowing frame for everythign but the epic and hidden lvls.
