While stated that the bonuses do not stack with themselves, that is not entirely true. When the bonus AP granted by Crimson Pact interacts with ability power modifiers, such as Rabadon's Deathcap or Archmage, the bonus AP gained from those modifiers triggers more health from Crimson Pact. This creates a cyclic loop. The same is also true for health modifiers, such as Juggernaut and Cinderhulk.
For every 1% of a respective modifier grants an 0.035% bonus to the opposite statistic component.
The healing effect of Transfusion does not occur until the projectile returns to Vladimir.
If Vladimir has any Spell vamp he will be healed instantly, not waiting for the particle to return. He will be then healed by the particle as it arrives.
If Vladimir uses Sanguine Pool or Stasis item immediately after Transfusion or the target is behind Wind Wall, the healing projectile will fizzle and Vladimir will not be healed.
COST: 20% current health
COOLDOWN: 26 / 23 / 20 / 17 / 14
Active: Vladimir sinks into a 150-radius pool of blood, gaining 37.5% bonus movement speed that decays exponentially for 1 second and becoming untargetable for 2 seconds. Enemies who stand upon the pool are slowed by 40%, and are dealt magic damage every half second while Vladimir heals himself for 15% of the damage done.
When in Sanguine Pool, Vladimir is still stunned when passing through Veigar'sEvent Horizon. If he does this, he will remain in his pool for its duration and remain stunned when coming out of the pool form, if the stun has not expired.
Tides of Blood
COST: 30 / 40 / 50 / 60 / 70 Health
Active: Vladimir unleashes a torrent of blood, damaging all enemies within range.
Each cast of Tides of Blood gives him an Empowered stack that lasts 10 seconds and stacks up to 4 times. Each Empowered stack increases both the base damage  and cost of his next Tides of Blood by 25% per stack, and increases Vladimir's self-healing, health regen, and spell vamp effectiveness by a percentage that stacks multiplicatively with itself.
Hemoplague is a ground targeted area of effect ability that debuffs enemy units in the target location for 5 seconds. Debuffed units have all incoming damage amplified, and upon debuff expiration they take magic damage.
Hemoplague's amplification applies to its own damage, meaning that the effective damage and scaling are 168 / 280 / 392 (+ 78.4% AP).
Hemoplague has no cast time and affects the target area instantly. However, there is a 0.5 second animation time that prevents Vladimir from using Transfusion and Tides of Blood. Sanguine Pool, summoner spells, and items can be used during this suppression time.
Hemoplague will amplify almost all sources and types of damage, including damage from neutral monsters. Only true damage is exempt from amplification.
Percent damage modifiers stack multiplicatively, such as Havoc.
Casting Hemoplague on a recalling enemy will not cancel the recall, because the damage is delayed.