“the number of Shield Throw ricochets is reduced by half (rounded down)”
Read literally, this says that the amount of the reduction is rounded down. So if you have 3 ricochets, the amount of reduction should be 1, leaving you with 2 ricochets.
Observed behavior and presumed intention is that 3 ricochets are halved and then rounded leaving 1 ricochet. Language to accurately describe that function should be:
"“the number of Shield Throw ricochets is halved (rounded down)”