Guildmage

Arcane Tradition
Comments from the Finger: This one’s based on Mage of the Arcane Order from 3.5. Thanks to Sleepy Magus for helping out!

School of the Arcane Order

Wizards of the Arcane Order, better known as Guildmages, are spellcasters that belong to an arcane academy or guild which serves the same purpose: to educate fledgling mages and advance the understanding of magic as a whole. To that end, guildmages share arcane magical knowledge through a common nexus known as a Spellpool, and can prepare spells known by others by attuning to this source.
     Guildmages are not known particularly to specialize in a school of magic, but are instead free to generalize their understanding through the community of the Arcane Order. This makes them some of the most flexible spellcasters in the world, as they are free to prepare spells from diverse branches of magic with ease.

Guild Membership
At 2nd level, as an established and respected member of the Arcane Order, you can rely on certain benefits that membership provides. You can board at the Arcane Order campus for free, and browse its library or use its common laboratory at your leisure. Additionally, you form professional ties with other wizards and sorcerers in the guild, which may lead to alliances or job opportunities in the future.
     You must pay dues of 5 gp per month to the guild. If you miss too many payments, you must make up back dues to remain in the guild’s good graces and continue to access the Spellpool.

Spellpool
When you join the Arcane Order at 2nd level, you are granted a special arcane focus that allows you to call spells from the common source of guild members: the Spellpool. When you prepare spells following a long rest, you can choose to prepare two 1st level wizard spells of your choice from the Spellpool, even if the spells haven’t been copied into your spellbook. These spells do not count against the total number of spells you can prepare.
     The number and level of wizard spells you can prepare from the Spellpool increases as you grow in level and rank within the Arcane Order, as shown in the Spellpool Table.
     If your arcane focus is lost or destroyed, or if you fall out of good standing in the Arcane Order, you cannot access the Spellpool. You can replace your arcane focus for 100 gp.

Spellpool Table

Community Spellcasting 
Starting at 6th level, you can bolster your spellcaster allies. Whenever you cast a spell, each creature you choose adjacent to you has advantage on the next spell attack roll it makes before the beginning of your next turn.

Spellpool Recovery
At 10th level, when you recover spell slots using Arcane Recovery on a short rest, you can also re-prepare the spells you have prepared from your Spellpool.

Guild Regent
At 14th level, you are awarded the title of regent within the Arcane Order. When you prepare your spells following a long rest, choose one spell you have prepared from your spellpool of 1st or 2nd level. You can cast this spell without expending a spell slot until you take a long rest again.

Changelog: 5/27/16:
Spellpool: Spells do not count against your total number of spells known. More spells prepared.
Community Spellcasting: Provides allies advantage on spell attack rolls.
Guild Regent: You can cast one of your spellpool spells of 1st or second level at will.
5/28/16: Guild Regent: Fixed typo