Achievement: Still Alive - Kill Nexus on Impossible - Helpful Tip

[Zelmont]

After spending hour or two trying to figure out how to defeat Nexus, the last boss of the game on Impossible difficulty - I came with a foolproof method of how to do it.

Each of his forms can be killed by two Orbital Bombardment. Presuming that you can beat the easiest one - the first one - without Orbital Bombardment, you just need to collect 4k gold to buy 4 Orbital Bombardments.

For me the fastest way to get the money was to use Blue Dragon hero, and go to 33 Portal stage (the one where the wolfs constantly spawns and every 33 seconds a Raax Portal appears) and just use the hero ( who flyies and can't be hurt by the wolfs) to destroy all 3 pillars. You can even do this with a lvl 1 hero. No matter what difficulty you pick, you will get the same reward - so make sure to farm this lvl on Casual - you get 420 coins per game and one game takes only 2-3 minutes.

Once you get the money, you just need switch to Impossible, buy Orbital Bombardments and bomb the boss into oblivion and waltz your robo-turtle buddy to the portal.

Hope this will help somebody, cheers!

[ThanatosX]

Worked for me, had given up on the last 2 achievements because this level was such a pain in the arse. Nice that you can just cheese it since they never adjusted the difficulty.