Can Volibear's legend ability trigger multiple times per turn to generate multiple runes when playing multiple Mighty units?

Ruling: Volibear's legend ability triggers and creates a chain each time you play a Mighty unit, but you can only generate one rune per turn because the ability requires you to exhaust Volibear to channel and get the rune. Once exhausted, you cannot use the ability again that turn unless you untap Volibear through another method.

Sequence:

• Play a Mighty unit
• Volibear's legend ability triggers and creates a chain
• You may exhaust Volibear to channel and gain a rune
• If you play another Mighty unit that turn, the ability triggers again and creates another chain, but you cannot exhaust Volibear again to gain another rune (he's already exhausted)

Nuances:

• The ability still creates multiple chains when multiple Mighty units are played, even though you can only get one rune
• Even effects that play multiple units do so sequentially, not simultaneously
• You could potentially get multiple runes in one turn if you have a way to untap Volibear between playing Mighty units