Hopefully can get a good thread going here to help each other figure out all the little nuances of the tables. Like: 
 
Secrets of the Deep  -   How do you increase the multiplier on the bottom left of the table? I've played the table TONS, but have never seen it budge even once.

I've no idea about increasing the multiplier, still yet to find that out myself,  but i do have a question regarding Rome... does anyone know how to start FRENZY? I'm trying to get the Legatus Legionis achievement - seize 7 garrisons OR start FRENZY - but even the Rule Sheet does'nt explain this?

Pinball FX could really use a nice how-to mode like Williams Pinball Hall of Fame has.
 
I don't know either of these things.

I remember e-mailing Zen a long long time ago, when the first Pinball FX came out, asking where i could find a rule sheet for the PinFX 1 tables and they told me they purposely withhold that information as it was more fun to discover on your own. 
 
But yeah, this would be a pretty good opportunity to write a game guide. The GB community can make our own rule sheet as we discover them. 
I say this out loud with hopes that someone else does it and i don't have to put in the effort.

"1. Hit the new species target on the right - twice, one to activate and a second time to activate the left plunger.
2. Get the ball into the left plunger through the left drain lane.
3. Hit the new species target with a skill shot."

1. hit the 3 species drop targets on the right (try view4...hard to see in view6) The targets periodically shift upwards. try to hit them when the targets are in the middle or top position. takes some practice to get the shot right. the targets reset after a certain amount of time or when you get a hull breach.
2. all 3 targets down; the left plunger opens up to where the left outlane is. Easiest way to make this shot is to load the cannon/periscope, and fire the shot directly into the left outlane, thus, into the left plunger.
3. Ball in plunger; One of the three species drop targets will light up. use the plunger to hit the lit drop target. Bottom drop target = minimum pull back, middle target = medium pullback, & highest drop target = maximum pullback. It will take practice to find how much pullback is required to hit each drop target.

Another question:
Does anybody know whether Rome has a skill shot and if it does, how to get it?
Thanks in advance :-)

 @PencilBastard: 
I haven't tried it out yet, but it makes sense, so thanks. 
About your problem: I found something on the rulesheet on the official Pinball FX2 page: The Probe Frenzy mode.  It says that if you get a certain number of successful probe launches, you get a chance to get a 2-ball multiball by shooting a second ball down from the magnet. You can then try to get up to four balls using the same method. The fifth ball will complete the mode and get you a score bonus.
I hope that is the multiball your looking for.