MArcomage

Give it some eefect if the condition isn't met, cause right now it's near useless in runic decks.

There should be at least 1 farsight common in your deck.

Anyhow - I redid whole thing to be even better, I think.

Dwarven artillery, Uncommon, 15b8r

Runic
If played after Farsight
Enemy highest facility -2
Else
Enemy tower -13


Ouch. Now that it's no longer Durable, this could only be discarded by a focused discard. Since the condition is entirely up to the player of this card, the opponent is left without any way to prevent its use. If this went live, it would be common to play this on turn 3 to set one of your opponent's facilities down to 1.

I would only let it work if the targeted facility is 5+, or perhaps just stating that it will not reduce the facility to a value below 3 (so it can put a 4 down one value to 3).

I also wondered if -13 tower without a condition isn't too much, but it's comparable with brick-cost Uncommons that reduce tower, so I'll let that one be.

capped facility reduction

That seems fair, although it does nerf the card quite a bit.

I think it could be phrased:
"Enemy Highest facility / 2 (Max -2)"
Resulting in -2 unless the highest facility is 3 or less.
Just an idea, I think it's closer to what you had originally since it DOES allow facilities to be dropped to 1, if they are at 2. But on the downside the phrasing is a bit more complex.

A little workaround - now it targets highest and lowest facilty for -1

That way you cannot get -2 for 1 type early on, and still be crippling enough. Also easier to get out.

Lowered tower damage a bit too.