The Devas Nero is a bonus content unit. When upgraded it has a 1% chance to instantly kill and a 35% chance to inflict darkness. With the ability to pierce shields, and doing approximately 50% more damage per second than a Nyon Exist. However, due to issues with it's projectile and poor stacking it is inferior in some ways to the Nyon Exist.
One major downside is it's high damage is based around a +225% damage boost which reduces the effectiveness of Chargors 13% boost to (100 + 225 + 13) / (100 +225) - 100 = ~4%. It is also about 50% larger than a Nyon Exist, however, it's hitbox is square, and thus despite being larger, is usually easier to place in a base than the oddly shaped Nyon Exist.
For a fuller comparison, read the comments below.
Ultra Amplifier: +35%-225% damage (10 levels)
- Cost: 3400, 3200, 5850, 9000, 12600, 16550, 20850, 25450, 30400, 35600
- TOTAL: 162,900
Encase: 10%-28% chance to inflict darkness (10 levels)
- Cost: 9000, 12750, 23400, 36000, 50300, 66150, 83350, 101800, 121500, 142300
- TOTAL: 646,550
Nirvana: Has a 1% chance to instantly kill. (1 level) (Cost: 375,000)
- TOTAL (for all upgrades): 1,184,450 gold, and $5 to a really awesome indie developer.
- = Cost with 25% discount upgrade
The Caligo Nox is exclusive to the mobile version of the game, and upgrades from the Devas Nero at Rank VII. Instead of firing slow Darkness orbs like the Devas Nero, the Caligo Nox fires Darkness missiles like that of the Zycon Storm.