Minions

The new minions are actually the summoners that needed a new job after the deletion of the league

Back then it was "soulless consturcts created by novice summoners". Without the summoners... Mindless servants summoned by the nexus as some kind of defensive reflex? In that case we would assume that the Nexus is kind of "alive"...

Minions are magical constructs, summoned specifically for use in battle. Earliest recorded use of minions for battles was at the battlefield known as Summoner's Rift where ancient sides, the Protectorate (Stag crest) and Magelord (Owl crest) summoners, fought against each other.

The process of minions spawning needs constant and massive amount of magical energy to be sustained. Minions are not fully sentient beings, rather they are controlled by the summoners who use a nexuses. The Nexus structure focuses enough magical energy from powerful crystals for sustained minion spawning and its destruction disrupts and stops the summoning magic.

There are many ways a minion body can be magically constructed, ranging from animated magic scrolls, magically animated bolts of cloth, and even sound. Also sand .

Necromancy is a minion summoning technique that uses dark magic to reanimate corpses. Like ordinary minions they are not fully sentient and are completely in control by the user who summoned them. Most known practitioners of necromancy come from the Shadow Isles .

Also, while not magically constructed, living minions share many traits as magically constructed minions. Voidlings summoned trough portals are controlled by those who have necessary magical power to use them, such known persons is Malzahar. A Celestial Being known as Bard is frequently followed by minion-like spirits known as Meeps that aid him in his tasks (though they are more like companions than outright minions).