This is the description of essence reaver:
+65 Attack Damage +20% Critical Strike Chance
UNIQUE Passive: +10% Cooldown Reduction.
UNIQUE Passive: Gain increasingly more Cooldown Reduction from Critical Strike Chance provided by other sources (maximum +20% additional Cooldown Reduction at 30% Critical Strike Chance).
UNIQUE Passive: Critical strikes restore 3% of your maximum Mana pool.
I wanted to know, if the critical chance of the item itself (20%) is getting involved here as well. When I for instance have 10% critical chance through runes and would buy essence reaver, would I gain 30% cdr instantly?