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The five Runestones have distinct, different, and dynamic effects on every skill in the game. As powerful and interesting as skill runes are, it makes more sense to think about base skills as "un-runed."

Though the D3 Team has only shown off a few of the skill rune effects to date, with all five effects known for Hydra, Weapon Throw, and Plague of Toads, one or two rune changes are known for quite a few other skills, and fans delight in speculating about what other effects the developers may have in store for us.

The Runestones page lists all known effects, with links to the skills where descriptions and screenshots are provided for your elucidation.