How to beat level 5.8?

[onomastikon]

I've got three stars on almost every other level, but I cannot beat the 80th wave (mobchain) on this map in 20 tries. Since I don't know what my problem is, I find it hard to ask more specific questions. Have a mixture of mostly mini guns, flamethrowers, venom towers which has been successful so far. Any tips appreciated.
As a side question, I'm not sure if this is a factor since it's never explained anywhere: when you retry a level, the big warning "minus 50% XP" - does that actually mean anything? Does XP equal EXP? Do towers get less experience when doing this map or is it something else?
Thanks in advance

[Tetsuya_Kurogane]

Grinding and better towers in general. (Can they level up to 20 for their ultimates?)
The uses of damage up modifier tiles, bounty for more coins and experience for those surrounding miners.

The XP on the level select page just refer to profile badge rank. This badge doesn't do anything, so it's not an issue.

[slup.kamil]

my help for beating this stage is just upgrade everything (global upgrades maxed, tower specific on lvl 7/10 or 5/5, 5/7 for upgrade levels), used a single of every "good" tower available at that time (cannon, multishot, minigun, venom, tesla, missile, flamethrower, laser) all placed on proper boosting tiles closer up to the path (sell price on cannon, attack speed on multi, power mult for mini, projectile speed for venom, damage for tesla, the attack speed further back for missile, XP mult for flame and laser is on the end of the path back there)
also buy a bunch of powers (around 5 fireballs, thunders, ball lightnings, smoke clouds, firestorms and nukes) and use those powers on constructor and mobchain (broot and stakey are very easy, just don't shoot broot when he's mad)
DO NOT PLACE ANY MINERS, SAVE THE MONEY FOR TOWER UPGRADES/MODIFIERS


also, the -50% XP only affects your profile level, which is basically worthless