alright, im coming back after the new 1.4.1 update and i've turned over a lot of my ideas before. lemme quick go over them.
Minions need more fixes.
One fix I have been DYING to have be added in is the ability for all minions to have local immunity frames, a feature that modders do with minions already. All it would do is make piercing projectiles deal damage and have to wait for their own immunity frames rather than the global I-Frame counter. This means minions like the Slimes would be able to attack more often and not be absolutely screwed over by the global immunity frames making them a lot worse than they should be. To counter how broken this could be, some minions (mainly around hardmode) would be slightly nerfed in order to make them only a bit better rather than by thousands of times over.
Whips need a replacement.
While yes, they do add a lot to the gameplay of summoner, they don't fit the theme well. sure, you could argue that it fits because of one thing that Final Fantasy does with their summoners, but whips are too out of place to feel like something that really fits well. My idea?
Squires.
Inspired by a mod that I currently sprite for, Amulet of Many Minions, (Go check it out, when you get the chance. its a lot of fun and I put a ton of effort into the sprites!) they would act as a controllable minion. They have a humanoid appearance and would have a variety of weapons. For example: a Mushroom squire, the first one you can get, which swings a little forest themed hammush thats been shrunken down a bit. These squires could have the tag damage as well to be applied whenever they hit an enemy, OR could be replaced with SUPPORTIVE SQUIRES. The idea is while you have one out, your minions gain a passive buff, such as a flat summon damage buff granting you an extra small minion for every 1-2 or so normal summons you have out.
Along with this, these squires could have their own armor sets and accessories, such as a drop from Skeletron like a little Skull Charm that summons a little spinning skull that will provide a buff to your squires while also dealing extra summon damage whenever their eyes flash, indicating a different buff to the squire, such as to their attack damage or speed and range of movement.
Armor
As it stands, the new armor in 1.4.1 helps a LOT. But, of course, with the changes i've recommended to the whip replacement, they will need some changes. So, what should be done?
First, non-Squire related changes: a new hat/hood for the Flinx Fur armor. Not only would this provide extra summon damage, it'd provide a set bonus that could do something like summon a little helpful snow flake minion like from the Cool Whip (seeing as it would be replaced, it'd be nice to re-use some of the effect from the whips) or it could grant a unique set bonus that grants your minions a special ability to sometimes summon little snowflakes around them that would slowly fall and deal some extra damage to their enemy. Along with that, replacing the whip bonus from obsidian armor would be a good idea. Maybe it could be a Squire related set bonus, but i'd personally just give it an interesting minion damage effect like the explosions that the Firecracker gives.
Next, i'd make armor sets focused around squires. Not too many, mind you: but enough to give squires a bit more love even if they won't have too many options (i'd be looking for around 20-30 to be in the game.) Some armor ideas are a Steampunk set, made with Cogs and perhaps Hallowed bars or some other sort of material, and for another idea, how about a pre-HM set based on the Granite biome, which is made from some kind of Granite-based material that can be obtained some time after Eater/Brain or Skeletron? The effects for squires could be buffs to their supportive abilities, maybe buffs to how they attack or how they mix with minions. The main draw back is that these sets would have less minion slots than normal provided, but provide a good bit more damage, like the Obsidian set does with Whips.
Accessories
This is honestly the biggest issue with the class, ignoring the Whips. The class only has a few select accessories, hell they only have ONE in pre-HM and its not even a new one, its just a hardmode accessory made obtainable early-game. I'd recommend adding more unique summon based accessories, like maybe a little Slime Pendant obtained from a new slime in the dungeons, which could have skulls and bones in them and drop the new accessory maybe around 5% of the time. It would give you a little summoned slime with a cutesy little wisp-skull in it that would attack enemies for you, along with granting extra minion damage of about ~10%. And for really early into the game, you could have a little worm in a can necklace or something that summons some type of minion upon killing an enemy.
Summoner also doesn't have an Avengers Emblem combo at all, which I think every class should probably have, even if Magic's is really scuffed and weak. I'm not sure exactly what it could do, but I was thinking it could be for something like a little desert based summon that would slowly build up little forbidden fragment colored hieroglyphs and would attack upon an enemy entering the screen, and of course it would scale with minion damage.
Anyways, that was everything I had in mind. It's pretty obvious these changes won't all be made, considering that 1.4.1 is probably the final content update for a very long time, if not forever. Maybe i'll get these added in Amulet of Many Minions with the dev, though. Again, check out the mod. It's really cool and i've been helping out with the spriting. As an example, here are a lot of the sprites i've gotten planned to be added. Some are already in, others are planned to be added in the next update. Sorry if this maybe a bit TOO much self-promoting, but i'm really proud of these sprites and the ideas the mod dev has come up with are really good and it's been a blast not only spriting for the mod but also just playing it. Check it out when you have the chance!