Sivir's Boomerang Blade returns to her after reaching the max range, so you can shift position to hit enemies who would otherwise have evaded it.
Try saving Spell Shield for enemy abilities that can disable you such as stuns and roots.
Ricochet resets Sivir's basic attack timer on activation, so activating this immediately after landing a normal basic attack will maximize damage output.
The stats shown on this page show several important Sivir versus Viego counter stats that may help you appreciate the differences and similarities between the two. As an example, Sivir’s KDA ratio ([kills + assists] / deaths) of NaN is better than Viego’s KDA ratio of NaN, highlighting that Sivir may be more central to her team's team fighting potential than Viego..
Sivir normally has a slightly smaller longest kill spree than her enemy does. Typically, she takes less damage than Viego. This commonly reflects different amounts of tankyness, yet it can also imply that the one champion has less mobility and thus is unable to flee from further harm when engaged or poked.
Both League champions are great. Both champs have their strengths, weaknesses, and counters. In League's current meta, Sivir usually loses when facing off against Viego, with a 46.2% win rate. Thus, Sivir makes a poor counter to Viego.
While Sivir does have a lower win rate compared to Viego, when they face off with one another, Sivir also has a lower learning curve that makes her a less complex champion to develop with. You should be very concerned when picking Sivir into Viego.
Additionally, Sivir has almost no amount of utility and CC, a similar amount to Viego. This often makes her just as valuable during teamfights, especially when fighting champions with a lot of burst damage.
While there isn't a single best champion for every situation in League of Legends, in Sivir vs Viego matchups, Viego is the better champ with a much lower win rate, less champion complexity, and a similar amount of utility to help out your allies during late stage team fights.
Sivir is a terribly counter to Viego. You will do well by focussing your actions on maximizing your CS and taking out objectives. If you are able to do that, you should do very well as Sivir against Viego.
To truly master Sivir to counter Viego during both the laning and mid / late game phases of League of Legends, you should keep reading to pick up a few extra lessons on this matchup. If you listen to the build and stats displayed above, you should increase your win rate by a lot and be closer to League of Legends pro players.
Sivir usually accumulates much more CS as Viego. Champs who on average don't earn much CS usualy don't need much CS to be valuable teammates, such as support champions. They are capable of scaling well off of their abilities and first items alone. Yet, champions with large amounts of CS, such as hyper-carries, usually need several high cost items to be effective. In either case, try to exceed the values shown on this page to do well.
The most important items to use in your Sivir versus Viego build include Phantom Dancer, Kraken Slayer, and Navori Quickblades. When Sivir included at least these three pieces in her build, she performed a lot better countering Viego than with most other commonly used counter builds. In fact, Sivir had an average winrate of 46.2% when countering Viego with this counter build.
To have the best likelihood of beating Viego as Sivir, Sivir players should equip the Lethal Tempo, Presence of Mind, Legend: Bloodline, Coup de Grace, Biscuit Delivery, and Magical Footwear runes from the Precision and Inspiration rune sets. Out of all the rune sets players picked for Sivir vs Viego fights, this order of runes resulted in the best win rate. Notably, these runes gave a 46.2% winrate overall.
If you would like to view Sivir versus Viego tips and counter builds for a a distinct rank, please select one from the selection menu shown above. If viewing for the first time, the stats and strategies shown are computed using every round played with these champs.