Lol bouncing mastery :P It might work, but here's a better mana-gain setup (worked for me on lvl 78 :D ) max slowing and max mana tap, some points in trap specials and trap layer... 1 slowing gem in a trap (first spot next to main spawn place) then 2-3 mana tapping gems in traps right next to it, then another slowing one etc etc.... WORKS WONDERS :)
O, advice here: If ure certain that no bloon will leave the screen, go to a tab or scroll down to comments, that way the game will b 3 times as fast :P (there will b no lagg :D)