Favor of Tzeentch

is a prayer with an answer value of 3 and a range
of 18". If answered, pick 1 friendly Slaves to
Darkness Mortal unit wholly within range and
visible to the chanter. You can add 1 to save rolls
for attacks that target that unit until your next
hero phase. In addition, if that unit has the
Tzeentch keyword, until your next hero phase,
you can roll a dice each time that unit is affected
by a spell or the abilities of an endless spell. If you
do so, on a 4+, ignore the effect of that spell