Hello,

Retribution of the Ancients reads:

{B}, Remove X +1/+1 counters from among creatures you control: Target creature gets -X/-X until end of turn.

Expected behaviour:

X = 0, I should be able to use the ability for {B} only.

Actual behaviour:

I cannot use it for X = 0! There is no stipulation that X cannot be 0 in this case.

Thanks very much!
-- Ronald L