Steelswarm Operator + Agatha's Soul Cauldron + Simic Ragworm

Steelswarm Operator

Agatha's Soul Cauldron

Simic Ragworm

How it works

1. Activate Steelswarm Operator's second ability by tapping it, adding that can only be spent to activate abilities of artifacts.
2. Activate Steelswarm Operator using Simic Ragworm's ability by paying , untapping it.
3. Repeat.

This clever loop begins by getting Simic Ragworm into your graveyard, where Agatha's Soul Cauldron can exile it and place a +1/+1 counter onto Steelswarm Operator. Because of Agatha's Soul Cauldron's static ability, that counter grants Steelswarm Operator the Ragworm's untap ability. You can then tap Steelswarm Operator for its restricted mana and spend a portion of it to pay for the borrowed untap ability, generating an infinite surplus of specialized blue mana to fuel your artifacts.