This generates infinite coloured mana of any colour, requires an additional red mana source to get going.
- Tap Basalt Monolith for 3 colourless mana.
- Spend that mana to activate its untap ability, holding priority while that ability is on the stack.
- Pay an additional red mana for Kurkesh, Onakke Ancient's triggered ability, copying Basalt Monolith's untap ability.
- Let one untap ability resolve, holding priority to tap Basalt Monolith for 3 colourless mana. Let the other untap ability resolve, tapping Basalt Monolith again for another 3 colourless mana, netting 6 colourless mana.
- Spend 2 of that 6 colourless mana to activate Signpost Scarecrow's colour filtering ability to filter to 1 red mana. Total mana: 4 colourless and 1 red.
- Spend three colourless mana to activate Basalt Monolith's untap ability, and using the 1 red mana to pay for Kurkesh's triggered ability, copying the untap ability.
- Repeat steps 4-6.