I will open with Treks "A taste of armageddon" where they take 12^18dB to the shields and do not lose a single % of shielding.
Calcs i found (been annoying ICS warsies with em on factpile :D...)
dB rating (if you want to calculate energy intensity in watts/cm^2) is:
-
dB = 10log(Io/Iref), where Iref equals 10^-16 W/cm^2
-
12^18 = 10log(Io/10^-16)
-
2.66e19/10 = log(Io/10^-16)
-
10^2.66e18 = Io/10^-16
-
10^2.66e18/10^-16 = Io
-
Io = 1e267 Watts/cm^2
-
This is a rather large number (If a DS superlaser, for example, had an output of 1e32 J in a period of 1/10th of a second with a beam cross section of 100m^2, it would have an intensity of 1e31 W/m^2 or 1e27 W/cm^2 and it would take roughly 10 shots to match the energy deflected by the E-nil’s shields in this example).
For this discussion the shields must be hit by a weapon (no avoiding it with transphasic cloaks etc), all weapons are to be considered DET or DET comparable, outliers are not only allowed but insisted upon.
Oh and try to stay within canon.