il manuale dice che per uscire da una lotta si può fare una prova di lotta al posto di un attacco. Le prove si fanno con attacco base che cala?

Sicuro!

When you are grappling (regardless of who started the grapple), you can perform any of the following actions. Some of these actions take the place of an attack (rather than being a standard action or a move action). If your base attack bonus allows you multiple attacks, you can attempt one of these actions in place of each of your attacks, but at successively lower base attack bonuses.

...

Escape from Grapple

You can escape a grapple by winning an opposed grapple check in place of making an attack. You can make an Escape Artist check in place of your grapple check if you so desire, but this requires a standard action. If more than one opponent is grappling you, your grapple check result has to beat all their individual check results to escape. (Opponents don’t have to try to hold you if they don’t want to.) If you escape, you finish the action by moving into any space adjacent to your opponent(s).

Direttamente da d20 srd