B-Tier = situational or decent overall power.
Guinsoo's, IE, Nashor's, Titan's are S-tier on the right units/combos, but D-tier otherwise.
C-Tier: low flexibility, low power. Shojin is fine for item economy, but meh in general.
D-Tier: Blue Buff. Conduits punish it. No big AP or AD scaling trait this set.