Hi Mirek2! Heres the answers to your questions:
Pressing the ‘unlock max upgrade’ button for each turret in the Armoury will show a box containing a description of the special upgrade.
All burn damages do stack, up to a maximum of 4.
Nuke damage and artillery damage is completely separate. Nuke does 20,000 explosion damage plus 1000DPS for the napalm burn.
Artillery does the shown value in explosion damage plus the same in DPS which can be buffed or upgraded.
Shields and boosts from shielder turrets do not stack, only the greatest connected value is used.
Glad you’re enjoying the game!
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