Also, at least from initial testing, she is not shielding the correct champion, at least to my understanding. I am running an unkillable CB team where everyone is at 100%. I made sure Turvold has the lowest HP in absolute terms. The idea is obviously for Turvold to get an additional Shield buff to feed into his 20% more damage passive. However, it is Fu-Shan who is getting the buff instead. Again, obviously, everyone is at 100% because of the block damage.  Torvald has a shield after each attack coming from accessories (ring). However, Fu-Shan also has a Shield at all times because of Demytha. When Demytha does her A1, she would re-apply the shield on Fu-Shan, who is also the Leader in the comp. 

Fu-Shan - lead position, 33,699 HP

Turvold - second, 33,443 HP

Am I missing something? How is she picking priority if everyone is at 100% HP? Does the existing shield gets added to HP value - something like 120% HP? I can provide a video if necessary.