Getting first blood gives you extra gold and experience.
Tips
register
Esports / MOBA slang, calqued from English 'first blood' as popularized in DotA, League of Legends (英雄联盟 Yīngxióng Liánméng), and 王者荣耀 (Wángzhě Róngyào, Honor of Kings). Heard in livestream commentary; rare in formal writing.
mistakes
Pronounced yīxuè in this gaming sense (CC-CEDICT lists yi1 xue4). Don't confuse with 一血 (yìxiě) sometimes encountered colloquially — gamer usage standardizes on xuè.