[Concept] Ardent Censer rework
+ 
+ 750 gold = 
2400 gold
50 AP 45 MR +75% base mana regen
Passive - Path Chosen: You cannot purchase Athenes Unholy Grail if you have an Ardent Censer. Passive - Transcendence: Gain 1.75% movement speed per 25% base mana regeneration. Disables Harmony on other items. (Unique) Active - Incense: Emit fragrant smokes in a target area (300 radius). Allies within the smoke gain 30% attack speed and deal bonus 30 bonus magic damage on hit. Smoke dissipates after 6 seconds. (45 second CD)
is "meh" without other %BMR items, but buying it doesn't lock you out of buying 
if you really want it. It just disables the Harmony passive on it and instead uses Dissonance from Athene's.
So a %BMR item that prevents you from buying a Athene's is really counter-intuitive