The instant I open a door and see the entire room covered with runes, I'd be hooked. And that puzzle is a great payoff for it. What numbers did you use exactly? I'm thinking you would want it to be +4 to +6 to AC initially, so that the PCs would have to use the control panel if they wanted to hit. Then they might strategize later on, to turn it back to +AC while everyone used their healing surges or powers that attack Reflex. I wonder if just "to hit" and "to AC" would be an interesting enough puzzle then. What other options did you use?
I kind of winged it, because that is how I am wont to do things. But it sort of went like this:
* There were three brutes, each with a timer. the first had a timer of "1", the second "2", and three "3" (go fig!). At the start of each brute's turn, the timer would drop - if it was at "0", the brute could go normally. A PC could spend a minor action to thievery one of the dials, and if they succeeded, they'd move it back two spaces - but if they failed, the timer would drop by one. Since the DC was 30, it was pretty close (I know my thieves, and they have digusting thievery checks). If a timer ever hit "5", that brute was shut down permanently (this happened to one of the brutes)
* There were also larger dials on one ledge. The DCs here were two higher, but the advantage was you had a better firing angle down on the brutes on the lower floor (we were using 3D dungeon tiles)
* A PC could also use the dials to shut off the minions heading into the room - again, failure on this check meant MORE minions came in.
* Finally, PCs could change the sigil in the centre - the four settings were (And I made these up on the spot):
- Blue (+2 to all defences)
- Red (+1d8 to all damage)
- Green (if you start your turn in the square, +10 temp HP; if end turn in the square and are bloodied, heal 1d12 hit points)
- Yellow (no effect)
Were I to do this again, I'd drop the "yellow" effect, and change it to some sort of haste effect (maybe can make a basic melee as a minor action, and +2 speed or something?). The trick with the encounter was that the brutes got the same effect - but the players were talking about putting two people at the control panel, sort of "DJing" effects... and I really should have encouraged that. I also should have thrown in a "control the minions" capability or something. But, I didn't want to make it too complicated.