League Classic masteries guide
Three trees, thirty points
Masteries are the second half of Classic's out-of-game power system: 30 points spread across Offense, Defense and Utility trees, unlocking tier by tier. The notation everyone uses — 21/9/0, 0/21/9 — just counts points per tree in that order. Going 21 deep in a tree unlocks its capstone mastery, and those capstones (like Offense's Executioner, bonus damage to low-health targets) are usually worth building toward.
The standard splits
21/9/0 — carries and fighters: full offense for damage, nine defense points for lane durability. 9/21/0 — tanks, junglers and bruisers: enough offense for clears and trades, deep defense to frontline. 0/9/21 or 9/0/21 — supports and utility mids: gold generation, cooldowns, mana and movement from Utility. Almost every champion in Classic lands on one of these three shapes; our champion pages show each pick's split with the trees visualized.
Points that matter most
Within a tree, prioritize the percentage and per-level scalers over flat one-time stats: attack speed and CDR rows compound all game, and Executioner effectively multiplies your team's finishing damage. In Defense, the health and armor rows outperform the niche anti-CC picks for most players. Utility's gold-per-10 and experience masteries are quietly the best 'stats' supports can buy.
Masteries vs runes — where power lives
Runes outweigh masteries early (level 1 stats), masteries pull ahead late (percentage effects). Together they're roughly a free long sword, cloth armor and null-magic mantle at minute one — which in Season 3 laning is the difference between trading and being traded on. Set both up before your first Classic queue; the players who skip this step feed the ones who didn't.