Runes and Masteries
represent what you can do outside of a game of League of Legends to
improve your chances to win inside of the game itself. See, they allow
you to improve a champion's strengths or reduce their weaknesses. There
are a variety of Runes and Masteries, and they give a wide range of
effects. There are four categories of Runes:
Masteries should be familiar to anyone who has played a roleplaying or action roleplaying videogame in recent years, as they involve skill trees. Basically, you have a trio of skill trees (Offense, Defense and Utility). On level-up, you get one Mastery Point to allocate in any of the trees. Depending on the tree in question, you can improve your offensive abilities, your defensive abilities, or some miscellaneous abilities. You don't have to worry about ruining your account, as you can reset your mastery points at any time to change up. In fact, you will want a variety of mastery pages for different champions. For example, a champion meant to take punishment would receive greater benefit from the defensive skill tree than from the offensive skill tree.
- Marks - Marks usually give offensive boosts such as armor penetration and increased attack damage. If you find a non-offensive Mark, it is probably a secondary Rune and thus will have a reduced effect.
- Seals - Seals usually give defensive boosts such as bonus armor/level or bonus flat armor. If you find a non-defensive Seal, it is probably a secondary Rune and thus will have a reduced effect.
- Glyphs - Glyphs usually give magic-based boosts such as mana regen/level. If you find a glyph that's non-magic, it is probably a secondary Rune and thus will have a reduced effect.
- Quintessences - The best type of rune, but the rarest as well. At Level 30 you can have up to 9 Marks, Seals and Glyphs on a rune page, but you are only allowed 3 Quintessences. There are a few effects that are only obtainable on a Quintessences, but there are also other effects shared with the other three types of Runes. It's up to you to find which Quintessences are best for your limited slots.
Masteries should be familiar to anyone who has played a roleplaying or action roleplaying videogame in recent years, as they involve skill trees. Basically, you have a trio of skill trees (Offense, Defense and Utility). On level-up, you get one Mastery Point to allocate in any of the trees. Depending on the tree in question, you can improve your offensive abilities, your defensive abilities, or some miscellaneous abilities. You don't have to worry about ruining your account, as you can reset your mastery points at any time to change up. In fact, you will want a variety of mastery pages for different champions. For example, a champion meant to take punishment would receive greater benefit from the defensive skill tree than from the offensive skill tree.

