if i have astral heron and the discount is applied. can i play bellows breath repeat and have the 2 energy 2 power fully reduced? does it work with the repeat cost?

Yes. Astral Heron's discount ([2][A][A]) reduces the Energy and Power components of your next card's total cost — including the Repeat additional cost — so Bellows Breath (1E + 1P base, plus 1E + 1C Repeat) ends up costing 0 total.

Key points:

• Repeat's cost is an additional cost added during cost determination, and discounts can reduce additional costs all the way to 0 (Rule 356.4.f).
• Since you chose to pay the Repeat cost, it's considered "paid" even at 0, so Bellows Breath still executes twice (Rule 356.4.f.1).
• The discount is applied once to the combined cost (base + Repeat), not twice (FAQ #629). You only get one discounted card, so don't expect the Heron to also discount a second spell that turn.