Example: Iron Angel had Telepathy and the Mind Control Extra. Her player buys Penatrating Attack (3 times, Cost 4 PP - She is able to burrow past even another Telpath's defenses causing a -6 on an opponent's DC roll) on Telepathy and she is able to once in Mind Control someone easier (i.e. - 6 on the DC roll against Mind Control).
Am I way off?
This would give you a character that is very skilled in a power, without having a high degree of power. A Power Level 10 character could have a PL of 5 in something an yet have a very good measure of skill with the power.

This is also a great way to run a PL 5 campain, while allowing characters more points to spread around, or that very specialized character that is a Master at a power or group of powers...like Prof. X....
