Can the Overlord voluntarily discard Power cards already in play? (Not to gain threat, but to allow other Power cards to come into play)

Aloysius said:

The rules say you are limited to how many you have in play, not that you can't play any more than a certain number.

Thus, the (admittedly vague) implication is that you can play more but must immediately discard one of the power cards so that you do not exceed the maximum number.

In other words, effectively Yes.
The current FAQ and GLOAQ do not answer this, nor, as far as I can tell, do the rules, but I am pretty sure it was answered before by someone from FFG. 'Pretty sure' that is, not 'completely certain'.

Just for a dissenting vote, I would say no. Having played a bunch of boardgames with limits like that, I would have expected a phrase in the rules mentioning what to do if you play more than the limit. But, that's just my read of the rules. As was mentioned above, there is no hard and fast statement either way.

I've always played it as 'you've got your limit on the table, you are done'.

As an Overlord, I've always understood that a Power card in play is locked in for the dungeon. I could be wrong, and the rules might be vague, but I don't believe there's any rule allowing you to discard cards from anywhere other than your hand.

Just to mention it, don't forget that the power cards of LTs reinforcing the dungeon DON'T count towards the OLs Power Card limit.

As far as i can search there is no where written that there can be only one Power Card in play. The only restriction written is that the OL can only play 1 per turn.
The last line concerning Power Cards even explicitely state that: "and these abilities are in effect for the rest of the play"

Forcing to discard any open Power Card already in play when you play another one, seriously damages the OL's abilities to grow and thoughen up against the Heroes who get a lot stronger and better during the game.

So voluntarily discarding cards should never be an issue, imo.

I believe Road to Legend specifically adds a limit to the number of power cards that can be in play (and that limit is larger than one). There is no such limit in the normal game.

So i guess we have to assume that Aloysius is talking about RtL, and not "Vanilla".......