MArcomage

I had revealed Heavy cavalry in front of my Master hunter.
When I played Master hunter, Heavy cavalry was discarded,
and I got +6 to my tower (probably there is bricks card instead
of Heavy cavalry now).

It seems that Far sight effect has two parts of code,
one before card effect and one after. I think it is not
supposed to work like that.

I guess you're referring to hidden mode? In that case the correct behaviour would be to reveal the new hidden card instead of giving you +6 tower.

Yes, game has hidden mode flag. And new card is hidden.

It seems this behavior is intentional. Card is hidden at the end of card processing, so if card effect discards a card, the keyword processing has the new card marked as revealed. However, I agree that this is an issue and I will look into it.