Should WF and TF have a cap? For example WF would be 5 ilvl and TF would be 10ilvl and make it more rare depending on what difficulty you are doing. LFR would have the lowest chance while mythic would have a higher chance.
NH Raid
Base/WF/TF
LFR 875/880/885
N 885/890/900
H 900/905/915
M 915/920/925