Using Dominion as an example: An event super may have 600% bonus, 55% bonus from lethal, 15% bonus from your zodiac leveling, 25% bonus from the zodiac boost on a tower and 100% if you activate a booster. The total bonus applied to the base attack stat then becomes 795%.
The booster doesn't double all the other bonuses unfortunately.
More details are available below in the screenshot taken from Pennypop's help page.
[Click image to enlarge]
