How do you beat the final epic boss on Gemcraft?

Many of the epic bosses can be beatenb without banishing, but the final epic I had to make go round twice. I was level 50 when I destroyed the Guardian. Skills-wise I had More Initial and Maximum Mana, More Mana Gain Per Kill, More Mana Replenish Per Second, Lower Mana Cost for Gem Creating and Combining, Lower Initial and Incremental Cost For Buildings and Number Of High Grade Starter Gems fully upgraded, I had four skill points each on Powerful Gem Bombs and Pure Gem Mastery. My top tips are: 1. Put towers on each corner of the path (2 or 3) so you can move the gems around to follow the Guardian, causing more damage, but having 6 towers and loads of water pits on the first stretch of road to cause major damage. 2. Mana pool up to over 7080 (if no points on armor skill) and fill your mana bar so you can banish the Guardian. 3. When he/she/it is on the very last bit of road, slow down the speed and bpomb all your gems. If this doesn't work, keep trying. It took me three goes without leveling up to do it. Also, if you don't get the gems you want at the start, go into options and restart battle a few times until you get it. Here are the properties of each gem. Green - Poison

Yellow - Triple Damage

Red - Splash

Blue - Slow

Lime - Chain Hit

Orange - Steal Mana

Purple - Reduce Armour

Cyan - Shock