Re: two (sigh) PRE questions
I might suggest an alternative house rule, or an alternative method for handling the issue.
1. House rule: A second, subsequent presence attack is only worth half the dice that it otherwise would be. A third is halved again, etc. After one massive bowell loosening presence attack, a second one loses a little something. If they are spending all those points of PRE, they've earned the right to use them, but if you don't want your game to turn into a bunch of roaring mice you have a right as a GM to set some rational limit on the tactic.
2. Escalation. A few high PRE villains can be a fine lesson in humility for recalcitrant PRE abusers. The combat, however, rather than looking like heroes duking it out across the city skyline, will look like an episode of Crossfire. High PRE combat should be limited because while it can be effective, it is also silly looking in the long run.