It's that little innate ability that is so easy to forget. And if you are one of the following 10 champions, you are happy that passives are easily forgotten. A passive can often mean the difference between life and death, and you will see this frequently from the 13 most powerful passives in League of Legends.

I originally intended on listing the 10 most powerful passives.  But, it was just too hard to narrow it down to a top 10 and I wanted to avoid any qq'ing about Champion X not being on the list.

EDIT: Due to overwhelming response, I have added 2 more champions to the list, making it "The 15 Most Powerful Passives". Thank you for your comments on the forums and on Reddit :)

  • Riot Games

    Fizz: Nimble Fighter

    (Innate): Fizz's dexterity allows him to perpetually ignore unit collision and take 4 / 6 / 8 / 10 / 12 / 14 reduced physical damage from autoattacks.

    Either part of Fizz's passive would be OK as it's own ability. And because of this, Fizz's passive is very powerful. Don't underestimate the power of ignoring unit collision, it is the most useful part of Fizz's passive. Watch the video below and notice how Udyr struggles to maneuver around the creep wave. All the while, Fizz bounces in and out harassing.

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    Nautilus: Staggering Blow

    (Innate): Nautilus' basic attacks deal an additional 2 + (6 × level) physical damage and immobilize his target for 0.5 / 0.75 / 1 seconds. This effect cannot trigger on the same target more than once every 12 seconds.

    Staggering Blow makes Nautilus a top tier tank. His peel and lock down capabilities are virtually unrivaled (shhhhhhh, I know Ali, Leona, and Janna are on par with him.) Check out the video below and see why Nautilus' passive made the list.

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    Volibear: Chosen of the Storm

    (Innate): When Volibear's health drops below 30% of his maximum health, he will heal for 30% of his maximum health over the next 6 seconds. This passive effect has a 120 second cooldown.

    Who wants a mini-ultimate on an innate passive? Volibear does! Chosen of the Storm is the main reason that Volibear can be played as a tank. Besides that ability, he has no other innate tankiness. Check out the video below and see how deceiving tanky Volibear can get while is passive is active.

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    Karthus: Death Defiled

    (Innate): Upon dying, Karthus enters a spirit form, which allows him to continue casting spells for 7 seconds. During this time, his abilities cost no mana.

    What other character can get a pentakill from beyond the grave? OK, Brand can do it, Malz can do it, Cass, Vlad, Morg, etc. But who can cast an ultimate after they died, resulting in a pentakill? Karthus can! Example below...

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    Blitzcrank: Mana Barrier

    (Innate): When Blitzcrank's life is brought below 20% health he activates Mana Barrier, creating a damage shield that lasts for 10 seconds. The shield strength is equal to 50% of Blitzcrank's current mana. There is a 60 second cooldown before Blitzcrank can activate this effect again.

    Thanks for all of the comments about adding Blitz to the list. His passive, Mana Barrier, is basically a free heal bait. It gives Blitz unexpected tankiness at times he really needs it. It allows blitz to get right into the thick of things and still be able to escape with his life. If you want an example of how to properly bait your passive as Blitz, watch the video below.

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    Irelia: Ionian Fervor

    (Innate): Reduces the duration of stuns, slows, taunts, fears, snares, immobilizes, blinds and silences for each nearby enemy champion. 1 champion: 10% 2 champions: 25% 3 champions: 40% Radius: 1200 (sight range)

    "Hi, I'm Irelia. And my passive, Ionian Fervor, causes me to not give a single solitary f***." Chain CC is a bitch sometimes... Unless you are Irelia over there just not giving a f***! Watch below as Irelia escapes from several Nasus Withers and various other forms of CC.

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    Vladimir: Crimson Pact

    (Innate): Every 40 points of bonus health grants Vladimir 1 ability power and every 1 point of ability power grants Vladimir 1.4 bonus health. These bonuses do not stack with themselves.

    Crimson Pact is one of those abilities that Riot hates... You know the ones, the abilities that give you free stats. Vlad's passive makes the list because it's just free gold -> Buy AP, get health. Buy health, get AP. So, if Riot hates abilities that give you free stats. Why did they give Xerath a passive with free stats!? XD

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    Katarina Du Couteau: Voracity

    (Innate): After a kill or an assist, Katarina gains 25 gold and her cooldowns are reduced by 15 seconds.

    Kat's passive truly mimics her snowbally design. If you get lucky enough, you can ulti twice during a teamfight. That is the recipe for a great passive. Watch the video below as Scarra shows how to dominate with Katarina.

  • Riot Games

    Annie: Pyromania

    (Innate): After every 4 spell casts, Annie's next offensive spell will stun its target for 1.75 seconds.

    Pyromania is the ONLY reason why Annie is a viable champion. It's rare when hard CC shows up in the form of a passive. And, when it completely defines a champion, it becomes one of the most powerful passives in the game. (Yes, I realize that Kennen's passive is almost identical. The reason Annie is on the list and Ken isn't is because I believe that Kennen would still be good without his passive. Annie would not.)

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    Akali: Twin Disciplines

    (Innate): Discipline of Force – Upon obtaining 20 ability power, Akali's auto-attacks deal 8% bonus magic damage, increasing by 1% for every 6 ability power gained thereafter. The bonus magic damage doesn't affect towers, but it affects other structures. Discipline of Might – Upon obtaining 10 bonus attack damage, Akali gains 8% spell vamp, increasing by an additional 1% for every 6 bonus attack damage gained thereafter.

    Twin Disciplines makes Akali a force to be reckoned with. This is another one of those abilities that gives you free stats and it is crazy powerful. Twin Disciplines could have made it to #1 on the list. But, because you need a very specific rune page to take advantage of it at low levels, I put it as the 5th most powerful passive in League of Legends.

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    Ryze: Arcane Mastery

    (Innate): When Ryze casts a spell, all other spells have their cooldown reduced by 1 second.

    How about some sustained dps with your burst? Tah Dah! Ryze can combo... and combo... and combo... and combo... All day long! Similar to Kat's passive, Ryze's Arcane Mastery allows him to spam his spells (much more reliably than Kat.) This is another one of the passives that just makes the champion work. Watch below as Ryze takes full advantage of his CD reduction - resulting in a pentakill!

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    Tristana: Draw a Bead

    (Innate): Tristana increases her autoattack range by 9 every time she levels up (does not include level one). At level 18, the bonus is 153 (703 total range).

    Oh man, Draw a Bead is goot! Trist is pretty much the safest AD carry in the game because of her passive. This is due to her ability to position herself better than any other AD carry in the game. Watch the video below and notice how Trist can dish out huge damage to an enemy before he even gets close.

  • Riot Games

    Mordekaiser: Iron Man

    (Innate): 35% of the damage dealt from abilities is converted into a temporary absorption shield. Shield generation is only half as effective against minions and monsters. Maximum shield strength is 90 + (30 × level). The shield decays by 3% per second.

    This is another immensely powerful passive that I missed. Plus it is probably has coolest name of all the passives in the game. Iron Man makes Morde work. There is no other way of saying it. If he didn't have this passive, he would be beyond weak. And on an opposite note, imagine if any other champ had a similar ability... It would probably be incredibly overpowered. Watch below and witness the true power of Morde's passive.

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    Janna: Tailwind

    (Innate): Increases the movement speed of all allied champions by 3%. This bonus is lost while Janna is dead.

    Many would argue that this is the best passive in the game. In fact, I would go as far as to say that every jungler in League of Legends thinks this is the best passive in the game. That tiny bit of movement speed can often mean the difference between life and death. Not only for you, but for your entire team. Watch below as Janna is able to escape harm with the help of that tiny extra boost in speed.

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    Poppy: Valiant Fighter

    (Innate): Any damage dealt to Poppy that exceeds 10% of her current health is reduced by 50%. This does not reduce damage from structures.

    This is it, this is the ultimate passive. Poppy's Valiant Fighter turns a little girl into a nearly impossible to kill MEGAYORDLE!™ (patent pending XD) At 500 health and below, virtually every damage source from a champion is halved. One of the first things to learn when playing a Poppy is... Don't Dive Poppy!

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    And the worst passive award goes to... Evelynn: Determined Killer!

    (Innate): Damage received from enemy minions (not including jungle monsters) is reduced by 50%.

    WTF is the point of this passive? It seems like the passive is only useful when Eve is tanking a minion wave. Check the video below for an example of a summoner not understanding Eve's passive. XD