Does Rhasa the Sunderer's cost reduction apply when it is in the Trash, allowing cards like Spectral Matron to play it if the cost becomes 3 or less?

Ruling: Cards that check cost always look at the base cost, not modified costs. Spectral Matron cannot play Rhasa from the trash even if Rhasa's cost would be reduced to 3 or less by its own effect.

Nuances:

• This principle applies to other cost-checking effects like Get Excited and Defy as well
• Cost reduction effects on cards do not apply when checking eligibility for effects that reference cost thresholds