Summoner

As a wizard that specializes in summoning the Summoner has a closer bond with their familiar compared to other wizards so much so that they are able to enhance their familiar beyond the usual capabilities. Along with this they able to access summoning spells that are usually inaccessible to wizards. 

Summoning Savant

Beginning when you select this school at 2nd level, the gold and time you must spend to copy a summoning spell into your spellbook is halved, and you gain access to all conjuration summoning spells. The gold and time you must spend to copy other conjuration spells is halved as well.

Enhanced Familiar

Your bond over your familiar becomes stronger as does it power. You can now transform your familiar into any beast of CR 1/4 times your wizard level (maximum of 5) at the cost of CR times 10gp worth of material components on top of the initial cost; the cost to transform your familiar to a form of a beast its current CR or lower only costs the material components listed in the spell. You must have seen or have detailed information about the beast you are transforming your familiar into.

Your familiar's hit points now equal 2 times your wizard level.

Expanded Familiar

The list of available familiars is expanded once more to non-beasts, your available familiars now include: Boggle, Flumph, Manes, Blink Dog, Dretch, Mud Mephit, Pseudodragon (familiar variant), Smoke Mephit, Steam Mephit, Darkmantle, Dust Mephit, Gazer Familiar, Ice Mephit, Magma Mephit, Piercer, Worg, Fire Snake, Hippogriff, Imp (Familiar Variant), Quasit (Familiar Variant), Quickling, and Pegasus

The same material cost increase and health increase from your Inhanced Familiar feature applies to these familiars as well.

Summoning Expert

Beginning at 10th level, while you are concentrating on a summoning spell, your concentration can’t be broken as a result of taking damage. In addition, if your concentration is forcibly broken and the summoned creature remains (as per the spell instructions) the creature does not become hostile to you or your allies unless attacked, however, it is no longer considered an ally for the purposes of spells and positioning.

Durable Summons

Starting at 14th level, any creature that you summon or create with a conjuration spell has 40 temporary hit points.