Credits Kyrasis#9330 from the Blood DK Discord for the suggested proper use of Blood Tap
This WA will trigger on either of the following conditions:
[1] [Blood Tap] if (you have 2 charges or are less than 5 seconds away from 2 charges of [Blood Tap]) and you have less than 3 Runes.
[2] [Blood Tap] if you have 1 charge, less than 3 Runes, and have less than 63 RP.