({5} magic symbol) ({U} magic symbol) ({R} magic symbol) plus enough mana to pay for commander tax, if applicable available.
Steps
Activate Thran Forge by paying ({2} magic symbol) , giving Sphinx's Disciple +1/+0 and causing it to become an artifact until end of turn.
Cast Idris either from your hand or from the command zone by paying ({1} magic symbol) ({U} magic symbol) ({R} magic symbol) and commander tax, if applicable.
When Idris enters the battlefield, its imprint ability triggers, targeting Sphinx's Disciple.
Holding priority, activate Strionic Resonator by paying ({2} magic symbol) and tapping it, copying Idris' trigger, targeting Basalt Monolith.
Resolve both Idris triggers, exiling Basalt Monolith and Sphinx's Disciple.
During your next turn, activate Idris using Basalt Monolith's first ability by tapping it, adding ({C} magic symbol) ({C} magic symbol) ({C} magic symbol) .
Activate Idris using Basalt Monolith's second ability by paying ({3} magic symbol) , untapping it.
Sphinx's Disciple triggers, causing you to draw a card.