The following are two sets of  'official' amendments, two lots of errata of, plus quick reference sheet:

Warmaster Ancients Rules Update 1:                  pdf 1

Warmaster Ancients Rules Update 2:                  pdf 2 (Note that some of the latest updates replace the skirmishing mod in the first update ‘2. Skirmishers—Evades from close range become subject to chance’)

Warmaster Ancients errata:                                  pdf 3

Warmaster Medieval errata:                                 pdf 4

Warmaster Ancients quick reference sheet:         pdf 5 (where to look for info by Vince Obrien)