Can you activate a mana ability while another spell or ability is on the stack?

Mana abilities are a special category of activated or triggered abilities that produce mana as part of their effect. A key property of mana abilities is that they do not use the stack — they resolve immediately when activated (CR 605.3a). This means they can be used at virtually any time, including when spells or abilities are already on the stack waiting to resolve.

The most common use case is paying a cost that requires mana. Whenever you need to pay mana — whether it's for casting a spell, activating an ability, or paying an additional cost — you can tap lands or activate other mana abilities freely, even mid-resolution of another action (CR 605.3b). Players also get priority to activate mana abilities in many timing contexts where they otherwise couldn't cast spells.

Concretely: suppose your opponent casts Lightning Bolt targeting your creature, and you want to activate Teferi's Protection in response. You can tap your Plains for white mana to help cast it even though Lightning Bolt is on the stack, because tapping a land for mana is a mana ability and doesn't go on the stack itself.

Note that not every ability that produces mana is a mana ability. An activated ability is a mana ability only if it could produce mana and doesn't have a target (CR 605.1a). Abilities with targets that happen to produce mana do use the stack normally and are subject to normal timing rules.