Teach by Example by paying ({UR} magic symbol) ({UR} magic symbol) , copying the next instant or sorcery spell you cast.
Cast
Reality Spasm by paying at least ({3} magic symbol) ({U} magic symbol) ({U} magic symbol) , targeting at least three permanents and choosing the untap mode.
Teach by Example triggers, copying
Reality Spasm, targeting at least three permanents.
Holding priority, activate at least two mana-producing permanents you control by tapping them, adding at least ({1} magic symbol) ({U} magic symbol) .
Activate
Errant by paying ({1} magic symbol) ({U} magic symbol) and tapping it, copying the
Reality Spasm copy, targeting
Errant and at least two mana-producing permanents you control.
Resolve the copy of
Reality Spasm from step 3, untapping
Errant and at least two mana-producing permanents you control.
Repeat from step 4.
Notes
It is recommended to pay at least ({1} magic symbol) extra when casting
Reality Spasm initially. If you choose not to, you will not get infinite untap of permanents or mana from those permanents, unless one of the mana-producing permanents taps to produce two or more mana.