Blizzard clearly had a few basic requirements when coming up with the communication system for Hearthstone:
1) Allow people to communicate a few basic concepts.
2) Don't allow them to be abusive of each other.
3) Don't require them to understand each other's language.
As such, you get a basic list of six "emotes" you can convey and the ability to "squelch" the other player if they're annoying you with them.
The six basic ones are:
- Well played
- That was lucky!
- Ow, that hurt!
- Nice try!
However, I'm pretty impressed that I've been playing for weeks now, and I only miss three phrases (and two of those are variants on "Well played", which does exist).
Original post on Dreamwidth - there are comments there.