Yes, the clock is counting down from twenty.So, looking at Promathia's screen shots that include a scoreboard, I'm guessing that the time shown at the top is counting down from 20 minutes. Is that correct?
And in the next section, do the three horizontal sectioned bars show you which guilds are claiming the three altars? If yes, what do the colored bars there tell you? And what's the purpose of the colored bar at the bottom next to, I'm guessing, your own guild name?
Edited to add: Do the circular icons at the bottom of the scoreboard "do" anything or are they just decorative?
Edited to add: Does the [Vvv] message that shows up in guild chat ever tell you which city has an ongoing battle? It just says "the city" in the message I see in one of Promathia's screen shots.
The bars show you the top three guilds progress towards winning the match. Th bottom is your own guild. Only one altar is active at a time, and the altars are only one way to gain points towards winning the match...aside from kills, citywide occupation, and stealing the sigil.
The icons are currently decorative, we may use them as a way to indicate the city is or is not being occupied as the message is currently a little spammy.
You get a message when you log in and when a battle starts via guild messaging.