Heave112: He can be good if u can reach the enemy adc every fight. I wouldnt pick him if they can kite u easily. Rek Eve Nida are very good early and u need to make their ganks work. That way u can snowball the game but u need to be active. Their overall winrate is **** but they can have very high winrates.
Elunwe: Kalista, Jinx, Sivir, Vayne i would say. They all deal sick dmg or have high teamfight impact.
slim: yeah i saw that ^^. Well i knocked up vlad the second he came out of the pool else we both wouldve died probably. But yeah that was 95% Froggen

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Kuroko: Well if u look at it from a time perspective u can probably surrender. But if u want to have as few losses as possible then u should keep playing. Its possible to win 4v5 and sometimes they come back or one of the enemy team dcs. U never know.