What Nettle said about Cad split is a perfect time to cast. With a SCH popping a quick Alqo before the split as well you definitely give the OT a better chance in gaining threat.

Not too sure if this worked but in T2 I had a WHM cast Stoneskin regularly to reduce stacks if it was timed well enough.

Well that's what he said anyway. I was too busy silencing and switching with the OT to notice.