MANAHIVE

There are currently very few red Battle—Siege cards. Here are the most similar ones to Invasion of Regatha, all in red:

• Invasion of Kaldheim — Red Battle — Siege. When it enters, exile all cards from your hand, then draw that many cards. You may play exiled cards this turn.
• Invasion of Azgol — Black/Red Battle — Siege. When it enters, each opponent sacrifices a creature or planeswalker and loses 1 life. (Not mono-red, but shares red.)

There are no other mono-red Battle — Siege cards with direct damage effects. The closest available is Invasion of Regatha itself.

Reason: Only a handful of red Siege battles exist, most directly reference Invasion of Regatha or are multicolor.