The Sivir and Friends comp is arguably the strongest and most popular comp in the current Patch 10.1 meta. The comp relies on the 4 Blademaster buff with Sivir as a primary carry and Azir as a secondary carry. With the meta's lack of Assassins and the addition of Karma, Sivir and Azir are often unharassed and can output tremendous damage from the backline.
This is a guide to winning with the Sivir and Friends comp.
This comp's early game has a similar goal to most other comps: you want to have a good balance between being as strong as possible, with the minimal amount of gold invested, and an easy way to transition to the comp's mid game.
The ideal early game units are Leona for frontline (Leona is one of the strongest 1-cost units in the game right now), Vayne to hold Sivir's items, and Karma to activate Lunar with Leona. However, most of the time you won't find the units you're looking for in the early game since you want to save gold and jump-start your economy. As such, you'll have to scrape together the strongest possible comp with what the game gives you. Some examples include: Woodlands and Druids, Renekton, Nasus, and Electrics (Volibear and Orn).
Although 3-cost units are expensive and you shouldn't keep them early, there are a couple 3-cost units that you MUST keep for this comp because they're so contested. The two units are Sivir (I know, surprising) and Azir. When you find a Sivir or Azir, grab them and hold on to them for your dear LP.
Another tip is to level up early, especially if you're naturally finding upgrades and fielding a strong early game comp. The reason to do so is because you really want to find Sivir and Aizr, and the higher level you are, the more likely you'll find them. Common aggressive leveling points in the early game are at stage 3-1 and at stage 3-4 (right after stage 3's carousel).
The most important items for this comp are Sivir items and a Blade of the Ruined King (BotRK) for Azir. Sivir's favorite items are a combination of: Infinity's Edge, Giant Slayer, Hush, and Red Buff (only the worse case). BotRK allows the comp to not only get 4 Blademasters early, but also complete all important synergies by level 8.
As such, important early game item components to secure are spatulas, bows, cloaks, swords, and gloves.
In the mid game, your main goals are to find a Sivir 2 and bring up 4 Blademasters and 2 Deserts. The ideal mid game frontline is an Aatrox 2, Yasuo 2, and a Yorick or a Leona 2 (depending on which comp variant you're going for). The main variants for this comp are Summoners and Mystics. The Summoners variant is stronger but also more costly and contested. The comp variant you choose to go for depends on the units you find when rolling down at level 6 and 7, and what the rest of the lobby is going for. For example, if Yoricks are highly contested, the Mystics variant is likely the safer bet.
Pay attention to your frontline
The comp's biggest weakness is a weak frontline in the mid game since you want to run 4 Blademasters but they often won't be upgraded since there're only a select few Blademaster units. Blademasters are already bad tanks and 1-star Blademasters form a paper thin wall. As such, you should pay particular attention to your frontline and if you're getting rolled over by, for example, Berserkers, you might want to drop the 1-star Blademasters for upgraded Wardens and temporarily settle for just 2 Blademasters.
Having a Leona 2 really helps this comp's frontline in the mid game. I can't stress enough... Leona is a powerful tank.
As you're building Sivir items, you can also consider powering up Azir as a secondary carry. Azir's best items are Jeweled Gauntlet, Infinity's Edge, and BotRK. Although I recommend prioritizing Sivir items (even over BotRK), if you do find rods, excess gloves, or excess bows, they should more often than not go on Azir.
Although it's better for you to roll at level 7 or higher for most comps, because this comp's main carries are 3-cost units, you can and should roll aggressively at level 6 to secure your Sivirs and Azirs. The only exception to this is when you've scouted and at most one other player in the lobby is going for this comp. In that case, you can greed and roll at level 7 without the risk of having all the Sivirs and Azirs hijacked.
An example mid game comp
Your late game options depend on which comp variant you're running.
The Summoners variant is extremely strong and synergy-tight. Once you've assembled this variant at level 8, you'd rarely want to replace its units and are probably best off saving up for level 9. At 9, you have the option to add in a random strong standalone unit (e.g. Amumu 2 or Taric 2) or drop 3 Summoners for 4 Mystics (i.e. replace Annie with a Nami or Master Yi).
Compared to the Summoners variant, the Mystics variant trades Yorick (currently a highly contested unit) and Summoner buff for 4 Mystics and 2 Clouds. Your frontline is slightly weaker but you'll run over magic damage comps and Cloud buff is very valuable against the rampant auto-attack comps in this meta. At level 8, you can either roll for an upgraded 5-cost Warden to replace Leona (e.g. Taric or Amumu) or get to level 9. At level 9, you can either play one more Warden (ideally a 5-cost Warden) for Warden buff and shore up your frontline, or replace Leona with Yorick and add in another Light unit for Light buff.
What about Lux?
The best Luxes for this comp are Cloud, Steel, and Crystal. Cloud Lux let's you activate 3 or even 4 Clouds, which is very strong in this auto-attack meta. Because Steel / Crystal Lux activates Steel / Crystal buff by herself, these two Luxes are the classic tanky Luxes that you can place in any comp with an empty slot.
- Infinity Edge: when Sivir ults, her auto-attack's bounces can critical hit as well, allowing her to deal significant burst damage to the enemy team
- Giant Slayer: Sivir's auto-attack bounces proc on-hit effects and Giant Slayer's extra damage is an on-hit effect. Giant Slayer is similar to Infinity Edge in that it allows Sivir to deal tremendous damage when she ults. The extra attack speed on Giant Slayer is also very valuable
- Hush: a classic Sivir item that lets her silence multiple units at once. Hush's chance to silence was reduced in Patch 10.1 and it's no longer a must-build on Sivir
- Red Buff: Red Buff's effect is also an on-hit effect and synergies well with Sivir's auto-attack bounces. However, Red Buff doesn't do a lot of damage and the burst damage from Infinity Edge or Giant Slayer is preferred. Only build Red Buff if you can't build the above 3 items on Sivir
- BotRK: almost, but not really, a must-have item for the comp. Besides making it easier to get 4 Blademasters, the item also synergizes well with Azir's spell since his summoned soldiers only attack when he attacks. An Azir with extra attack speed and the 4 Blademaster buff attacks a lot
- Jeweled Gauntlet and Infinity Edge: this item combination allows Azir's soldiers to deal huge burst damage. Infinity Edge amplifies critical hit damage and Jeweled Gauntlet allows the soldiers to critical hit
- Rabadon's Deathcap: Deathcap amplifies Azir's soldiers's damage, which is always valuable
- Morellonomicon: like Deathcap, Morellonomicon amplifies Azir's soldiers's damage and causes their attacks to apply Morello's debuff
- Guardian's Angel: a strong item on Yorick since it greatly increases his odds of casting his ultimate multiple times
- Bramble Vest: a strong item on Leona that makes her incredibly tanky, especially in the early game
- Redemption: Morellonomicon is less popular in this meta and Redemption's heal will often not be mitigated
- Thieve's Gloves: a generally high-value item that's best used for a frontline unit since it gives dodge chance
- Dragon's Claw: the classic defensive item against magic-damage heavy comps