I've been using the 4pc IK set bonus for a while and I've noticed a possible bug with Call of the Ancients.
When you cast Call of the Ancients you get a buff icon on your buff bar that they are up.
Seen here: i.imgur.com/CRLhsWH.jpg
Normally, this buff would run out and the Ancients would disappear at the end of the timer, however with 4pc IK they are always up.
The bug I noticed is that sometimes this buff icon goes missing but the Ancients will still be up. When this happens your ancients lose the rune affect.
For example I normally use the council rises (fire) rune for the extra damage since I stack fire. With the rune up they hit for around 8million BUT when the bug occurs they go down to around 2million just like is my rune is no longer affecting them.