Snowball

Snowballs are situations that gain momentum over the course of time, analogously derived from a snowball rolling down a hill, picking up more snow and momentum as it rolls. "Snowballing" generally describes the act of using so called "Snowball items".

Snowball items

Snowball items are items that make a champion stronger over the course of time, unless that champion is killed on a regular basis. While granting only low stats by themselves, the items allow the champion to gain stacks of a certain effect which further increase stats (e.g. bonus ability power or attack damage). Each kill grants two of these stacks, while an assist grants one stack. They do not retroactively grant stacks, i.e. kills and assists gained before the item was bought will not grant any stacks. The stack cap for the current set of items is 20 stacks. Upon reaching that cap, an additional bonus is unlocked for as long as no stacks are lost. When the champion dies, they lose a third of their stacks, rounded down. The stacks are bound to the item, meaning that if you sell the item, the stacks will be lost. Buying the item again will not replenish the stacks.

The snowball items give a buff upon receiving one stack. When you die, you lose this buff.

The snowball items and their buffs are:

• Leviathan - Leviathan Armor (item was removed)
• Mejai's Soulstealer - Soul Engourgement
• Sword of the Occult - Blood Tribute

Exceptional Snowball Items

With patch V1.0.0.145, the snowball item Bonetooth Necklace has been added, which is available exclusively to the champion Rengar, the Pridestalker who has been added in the same patch. The item differs from the above mentioned snowball items in the following manners:

• Upon obtaining charges, the icon of the item changes.
• Instead of giving one bonus that increases or decreases with stacks, the item grants several different bonuses depending on the number of stacks Rengar has.
• He does not get a bonus for every charge but for every threshhold of charges he achieves. The threshholds are 3, 6, 9 and 14 charges.
• Gaining and losing charges works differently. He always gains one charge when he kills or assists in a kill, and always loses one charge when he dies.

Cost efficiency

While snowball items grant comparably low base stats (especially compared to their gold prices), a fully stacked snowball item grants stats that exceed most other items in the game, let alone within their gold price range. Mejai's Soulstealer, for example, grants only 20 ability power at the cost of 1235 gold if the champion has not collected any stacks yet. At 20 stacks, however, it grants a total of 180 ability power as well as 15% cooldown reduction, surpassing Rabadon's Deathcap which costs 3200 gold, with any amount of stacks higher than 17.

From a cost efficiency perspective, Mejai's Soulstealer breaks even at 6 stacks (18.16 gold per point of AP) and Sword of the Occult breaks even at 5 stacks (34.28 gold per point of AD).

Semi-snowball items

Since they use a similar stacking mechanic, The Bloodthirster can be referred to as a snowball item as well. However, the stacking effect works very differently. Instead of stacking only on kills and assists,  The Bloodthirster also stacks on minion kills, enabling a champion with the item to fill it by simply killing minions and monsters before a fight. Only half of these stacks are lost upon champion death, so champions with this item often go after farm upon respawning.

Countering

As soon as you realise that an enemy champion is getting a snowball item, it is essential to keep them from gaining stacks and kill them as quickly and as often as possible; they should be your highest priority in fights. Keep in mind that each assist grants one stack as well, making team fights very attractive for snowballing champions. Also keep in mind that, after a snowballing champion is killed, assists will still grant them stacks even after death. This makes it considerable to sometimes kill them last in order to drain the most stacks from them. In the case of  The Bloodthirster, it would be wise to attempt to catch a champion farming while he tries to regain his stacks, since farming is usually done alone, and they won't have as much lifesteal as they did before death.