Another fun match-up that feels balanced.
When playing against SE, I tend to try to focus on killing commons to prevent any units from buffing up too much. However, for this match-up, I like to threaten Abua early which then limits his events later in the game (especially chant of power).
Although you still have to be careful, Tacullu's health and mind control let you keep early pressure on Abua.
Mind Witches are interesting in this match-up because they can take advantage of boost tokens by copying Rhinos and Border Archers. One reminder is that a Mind Witch that copies a Rhino can only trample through commons.
For Abua, I tend to try to keep him protected and then try to punish Taculla if he overextends.
Use the higher health units to wear Tacullu down and build towards an explosive turn.