Can I take any buffed unit to pay the additional cost for Call of Glory?

Yes, you can spend a buff from any unit you control to pay the additional cost for Call to Glory, regardless of where that unit is located (on a battlefield or in your base).

According to Rule 702.2.b.2, you can only spend buffs on units you control. Additionally, as noted in RiftJudge FAQs (e.g., FAQ #2868 and FAQ #5922), the ability to spend a buff does not restrict the location of the unit, provided you control it.

To summarize the requirements for paying this cost:

1. The unit must have a buff on it (Rule 702.2.b.1).
2. You must control the unit.
3. The unit can be at any location on your board (field or base).