Does floating mana from tapped runes reset after combat during special cleanups, or only at end of turn?

Ruling: Floating mana from runes only empties at end of draw step and at end of turn, not after combat during special cleanups.

Sequence:

• Floating mana persists through combat
• Floating mana empties at end of draw step
• Floating mana empties at end of turn

Nuances:

• If you exhaust 6 runes to accelerate, recycle 2, play a unit, then exhaust 2 more (leaving 2 floating), when your units die in combat you ready the 6 exhausted runes while the 2 floating mana remains available until end of turn