Breaking Power Level

So your GM has given you a power level, but you're just as powerful as every other character. How can you min/max break power level limits and make the most powerful character- and as a GM, what should you be wary of?

Tradeoffs- You can trade attack bonus for maximum toughness DC. This can double your effective power rating, but comes with the side effect of being unable to hit. You can trade defense for toughness. (This only really makes sense in favor of toughness since perception powers will wreck you otherwise). These tradeoffs also come in the form of feats that allow up to +5 to be traded off (power attack, accurate attack, all out attack, defensive attack).

Now, this might not seem so bad- a guy with high save DCs will never hit anyway, right? Well, consider the aim action, or ultimate effort (aim), and now you're making up for that deficit and getting all the benefit.

Improved Aim: You can get +10 by spending a full-round action aiming. Use extra effort to attack right away, or use ultimate effort to roll a basic 20.

At PL 10, you can give yourself a toughness save of 15(base), +20 (tradeoffs) = 35. The enemy (without tradeoffs) gets +10 to save, and must make a 25 or better to be fine(not possible), 15 or better to avoid stun, and 10 or better to avoid staggered.

Autofire Extra: This power extra can be taken 3 times.
1: For every 2 points you exceed the Defense of the target, get +1 to save DC, max +5 (or halfe attack level)
2: Now it's 1 for 1.
3: Now it's max +10 or the power level.

So autofire of 3, if you use aim and ultimate effort or something can grant you an extra +10 to DC. Now you're at toughness DC 45. They will always be at least stunned, and must beat 15 to avoid staggered.

Team Attack: This requires that the base DC is in line, but for every attack that hits you can get +2 to the save DC- no limit. This alone can crush damage limits.

Inspire: An ally could give up to +5 to attacks, skills, and saves for 1 round with a hero point. That can make up for those tradeoffs or boost autofire.

Critical Hits: +5 to save DC on a critical hit- and with improved critical you can easily make any attack that hits be a critical hit.

Master Plan: Can grant up to +3 to skill checks and an attack roll during an encounter, breaking PL limites.

So between inspire, aim, and master plan, you could get +18 to hit (above your regular attack), which is likely more than you had available BEFORE tradeoffs.

Cover/Positioning: Betters your defense. If you have Prone Fighting or slithering, you can get +4 defense against ranged attacks just from being prone, and suffer no ill effects yourself. Same thing from taking cover.

Concealment: Concealment provides 20% miss chance (or 50% if totally concealed). Total concealment can also block perception based attacks. So you can add concealment to super-high defense, and protect yourself from being hit on top of defense against perception attacks.

Weapons: A chainsaw can add +6 to melee damage by itself. This is on top of strength, which could  be bought way up due to tradeoffs and such. Above there was a save DC of 45, now we're at 51. The chainsaw may break from one attack, but with create object or summon or something you could have an endless stream of chainsaws, or chainsaws hard enough to withtand the damage. Even hitting people with cars or telephone poles can add some much needed damage on the fly.

Extra Effort: Extra effort can add +2 to the PL of an attack, or 2 ranks to a power (generally the same thing).

So now we can see all the in-game reasons you can "break" the power level limits in the game and make characters who cannot possibly be saved against, and not at a very high price either.