Backstab also applies after a critical strike is achieved. If you were to critically strike for 500 damage, the same critical strike would do 600 damage from behind (500 * 120% = 600 damage).
COST: 90 / 80 / 70 / 60 / 50 mana
COOLDOWN: 11 seconds after exiting stealth
Active: Shaco instantly blinks to a target nearby location and enters stealth for up to 3.5 seconds. Dealing damage will break stealth early. His next basic attack within 6 seconds is guaranteed to critically strike for modified base critical damage.
Deceive's damage bonus replaces the normal critical strike modifier, causing it to actually do less than a normal critical until the skill is at least at rank 4. It is affected by critical damage bonuses like Infinity Edge.
Deceive will apply bonus critical damage on top of its modifier. For instance, with Infinity Edge (+50%) and Rank 5 Deceive, Shaco will deal bonus damage equal to 170% of his attack damage (crit = 100% + 50% bonus from IE +20% bonus from Rank 5 Deceive) . This is before any other bonuses or mitigation are applied. Note that if Shaco were to attack the target from behind it would deal 20% additional damage on top of the critical strike itself making the total damage of the attack equal to 324% of Shaco's total attack damage.
i.e. Shaco has 150 attack damage:
Rank 5 Deceive crit from behind with Infinity Edge = [150 + ([1.20 + 0.50] × 150)] × 1.20 = 486 total damage.
Deceive's casting animation (an orange puff of smoke) can be seen by both teams through the Fog of War.
Jack In The Box
COST: 50 / 55 / 60 / 65 / 70 mana
Active: Shaco summons a box at the target location that stealths after a 2 second delay and lasts for up to 60 seconds. When an enemy comes within 300 units, the box springs open: causing surrounding enemies to turn and flee while it attacks nearby enemies for up to 5 seconds.
Active: Shaco vanishes for 0.5 seconds, then creates a clone of himself that will last for up to 18 seconds.
The clone deals 75% of Shaco's damage and receives 50% extra damage. This clone deals 50% damage to towers and inhibitors. At the end of its duration or when dying the clone will explode, dealing magic damage to enemies within 250-range.
Boxes will prioritize the nearest enemy champion that has damaged Shaco or that Shaco has damaged, preferring to attack that champion whenever it is in range, even if they have moved too far away before walking back into range.