is boosting reportable?

Playing on an account that is not yours is a bannable offense.

You can report them after the game or with a support ticket.

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like someone logging on to a bronze 5 account and see a visable difference in games type of boosting. if so how do i report said person cause theres no reason someone jumps in skill this much.

If by that you mean: Say for instance that you're a Diamond 2 player, and you log into your other account in Bronze 5, and proceed to dominate the game because you're literally a Diamond player in Bronze. Then that is not "boosting", but "smurfing". Smurfing is when you intentionally go to a rank lower than you really should be in with another account THAT YOU OWN**, just so that you can wreck the lower elos for your own personal pleasure. While Riot and most players are against the notion of smurfing, however outside of regions in which they have their own rules prohibiting the act of smurfing such as KR and Garena/China, otherwise smurfing is not illegal in Riot and League's terms as of yet and not punishable on the ground of smurfing alone.

"Boosting" is when you rank up another account that you DO NOT OWN**. And as clarified before, there are typically 2 types of smurfing, and only 1 of the 2 is outlawed.

1. The first form of boosting is when you use your smurf account (reference above for "smurfing") to engage in DUOING with ANOTHER player of the lower rank, in order to carry them into a higher elo the carried player do not belong in. This is a form of boosting that is not outlawed centrally because the notion of smurfing is currently not outlawed by Riot as outlined above.
2. The second form of boosting is when the higher elo player is PLAYING ON ANOTHER PLAYER'S ACCOUNT. It is a subcategory of "account sharing", ie Player A plays on Player B's account, something that is forbidden by Riot just to include this form of boosting. This "account sharing boosting" is when Player A (high elo) plays on Player B (low elo)'s account for the purposes of ranking Player B's account into higher elo bracket without the real owner even playing the game, and is the form of boosting that is acknowledged as illegal by Riot.

.........

**Regarding "OWNing" the account:

The "ownership" is defined by Riot by comparing the player behavioural profile built from collecting detectable facts and player biases as the player plays after the account's inception with the current behaviour of the player using the account. Such as where and how often you use an account in a given IP address, certain play habits such as Flash being put on which keys, preference in champions such as 1-trick or having handful of dedicated mains or a player dedicated in a certain team position or a generalist who pick champs almost by random, etc etc. And if a player's behaviour and pattern in any or any combination of these things change so much and/or so abruptly that the system does not think the account is played by the same person, the system detects it as another playing playing an account they do not "own" and bans it for account sharing (or in the case that the system believes the account is hacked, it will ban it to protect it and until the real user contacts with Riot).