Binding runes on a hero increases the hero's stats. Runes increase different stats depending on the rune.
Runes are also part of a set. The symbol on the rune and the name of the rune tells you which set it belongs to. If you collect and attach a complete rune set on a hero, the set will give an additional boost. One rune alone from a set will not give you the set bonus, only the full set gives the set bonus.
You get runes from chests that you get by completing story dungeons. Each chapter of story mode gives runes of a different rune set and quality so you can choose which set you grind for.
In Battlejack, you get to level up your Runes. In the beginning, you can level up a Rune with Gold, but when your Runes advance far enough, you need to start using both Gold and Rune Shards in order to level them up.
There is also an element of chance in leveling up. You might not always succeed in going up a level. Keep trying. Remember, you can always Dismantle some Runes you don't feel like using to obtain Rune Shards.
To Bind Or Not To Bind?
Let's say you're taking really bad hits in a dungeon and need increased healing. You can bind Recovery or Health Runes to your Hero - this will increase your Team's overall HP recovery while you pass through the different rooms of a Dungeon.
Pro Tip: Think carefully about the heroes stats - bind Life Runes that boost recovery and Health Runes to your Healer. This way, you'll get maximum benefits for health recovery and healing during the fight.
Pro Tip 2: If you read the previous tip carefully, you'll already be binding Attack Runes and Piercing Runes to your most powerful Heroes.
Go on, bind a Rune into your Hero!