Tectonic Tactician Feat 17

You've learned how to fight enemies without leaving the safety of your tunnels. Your tremorsense provided by Tunnel Vision becomes a precise sense. While underground, you can target enemies you detect using tremorsense with Strikes, Area Fire, and Auto-Fire as long as the only material between you and the enemy is something you could normally move through using your burrow Speed. Unless you use adamantine ammunition, ranged attacks made through solid ground have their range increments halved, and you take a –2 circumstance penalty to your attack roll for ranged attacks that pass through the ground.