Whether once lonely as a child or wanting to muster an army of creatures. A summoner brings forth a creature from thin air using their knowledge and memory of the creatures they've studied deeply.

Summoner Savant

Beginning when you select this path at 2nd level, you choose one of the following schools of magic. The gold and time you must spend to copy that school's spells into your spellbook is halved.

Abjuration, Conjuration, Enchantment, or Evocation.

Summon

Starting at 2nd level when you select this school, you can use your action to summon a creature that is equal to or lower than your class level (minimum CR 1), granted that you have studied it for at least 1 hour secondhand (Ie: books, notes, corpse, etc.) or 1 minute firsthand (Ie: in combat, scouting, etc.) 

You can summon up to a number of times equal to your intelligence modifier (minimum 1) before needing a long rest. When you summon a creature, your maximum HP is lowered by twice the CR, but your AC is increased by 1/3 the CR, rounded up. 

Creature restrictions are listed at the bottom. 

The Summon's HP is 9 x character level+int mod+pb. It can only go 120ft away from you, it can be commanded no farther. If the Summon is forced more than 120ft away from you, it disappears with no tax on your maximum HP. The Summon is not intelligent in the sense that it can think and move for itself, unless given a broad but not overreaching command (i.e.: guard this 40ft area). 

As a bonus action (for now), you can have the Summon take its turn using its description, and possibly more. If no command is given the Summon will take the dodge action. 

The Summon remains by your side for an hour, or until killed. If the hour is over and the Summon is not killed your maximum HP goes to normal. If the summon is slain your max HP remains lowered until you finish a short or long rest. Your max HP cannot be lowered below 1 in this way. Either way, you do not receive a Summon's AC bonus if you do not have an active Summon.

Listed Limits: The creature can't be a named creature, have legendary actions/resistances or lair actions. Furthermore, the creature cannot be a swarm, have the ability to cast magic or summon other creatures. (Your DM can allow you to do otherwise but I recommend removing that creature's ability to summon. It just breaks it.)  

The creature type you can summon include are but not limited to (at DM discretion): 

Beast, Construct, Elemental, Fey, Fiend, Giant, Monstrosity, Ooze, or Plant. 

Summons

Level	Max CR	Limitations	Example
2nd	2	No flying speed + LL	Giant Boar
4th	4	No flying speed + LL	Black Pudding
8th	8	Listed Limits only	Fiendish Flesh Golem

Summoner's Call

Starting at 6th level, you can use your action to swap places (teleportation) with your Summon up to 60ft. Alternatively, you can have your Summon teleport to an unoccupied space within 5ft of you from any distance (max 120ft). Neither provokes opportunity attacks.

Once you use this feature, you can’t use it again until you finish a long rest or you cast a spell of your chosen school of 1st level or higher.

Residual Transfer

You've learned to channel the backlash from a Summon's death into bolstering your defense temporarily.

Beginning at 10th level, when your Summon is killed it no longer keeps your HP lowered. Additionally, you keep the AC bonus until the start of the next round or you summon a new creature, whichever comes first.

Expert Summoner

Starting at 14th level, you've essentially mastered summoning. As a benefit of your knowledge and ability, when you summon you receive 30 temp HP until it is lost or you take a short/long rest.

Furthermore, the amount of times you can summon resets on a short rest now. 

Experimental: Additionally, your hunger for the knowledge of all things summons has pushed you into researching abstract summons. You've unlocked the ability to have 2 active summons at the same time.

When you have 2 active summons their combined CR cannot be more than half you character level.