i think the arrow skill is under-rated
it hits pretty much everything out in the open, it does decent damage (as much as the meteor), and it has a rather short charge time, a little more than twice the meteor (when at the same lvl)
mass wizards and mass hobbits can win from lvl 1 up to lvl 10 or so
just use arrows in the first few minutes to defend, upgrade both arrows, and max mana (increases the mana per second as well), after ur arrows r fully upgraded, fully upgrade academy, nothing else, then save up for about 5 wizards, get them out, and then spam "1" for hobbits (u will never run out of mana, because ur mana generation would be greater than 10 per second, much greater), whenever u get 400 mana again, get another wizard, and keep spamming "1", on the "revenge" lvls (where when u almost destroy their castle, and then tons of units flush out), just keep doing the same thing, and when they get within ur arrow range, use super arrows
The two types of monsters that can usually touch your gems (you can't get a brilliant if that happens) -
Ninjas - When hit, become invisible for an amount of time (use meteors)
Assassins - 50% chance to dodge an attack (effects can still affect them, so use the banshee towers)