Dark steel ingot

[Barberi1320]

Is the one extran mama added to the pool only until end of turn or does it keep building turn after turn?

{Darksteel Ingot}

[scarsabrex]

Till the end of the phase.

[Pleeb]

The mana pool is emptied between phases.

500.4.: When a step or phase ends, any unused mana left in a player's mana pool empties. This turn-based action doesn't use the stack.