About the Skill:
Spellweaving is a skill introduced with the Mondain's Legacy expansion. It is meant to encourage group spellcasting by giving a bonus for multiple arcanists working together. However, there is no need to stick together once they have obtained their Arcane Crystal.
New characters cannot start with the Spellweaving skill, it is a privilege that must be earned by completing one of two Quest Chains: Patience or Discipline.
Spellweaving also benefits from a Mastery: Enchanted Summoning, Mana Shield and Summon Reaper.
How to train:
To begin training, you must first complete either the Patience Quest in Heartwood or the Discipline Quest in Sanctuary. Upon completion of either quest, you will receive: a Spellweaving spellbook, an Arcane Circle scroll, and a Gift of Renewal scroll. To fill the rest of your spellbook you will either have to kill monsters in Mondain's Legacy dungeons or buy them from other players. Two spells, Summon Fey and Summon Fiend, can only be earned by completing certain quests.
Once you have your spellbook in hand you can begin training Spellweaving. The chart below represents the quickest and most efficient method of what to cast at each skill level.