So there are three possible interpretations to the unarmed strike rules, and all of them allow abuse:
1. You can make unarmed strikes with your hands, feet, and head(s), and only those body parts. Monks gain the additional ability to unarmed strike with their knees.
Combat wrote:
Unarmed Attacks: Striking for damage with punches, kicks, and head butts is much like attacking with a melee weapon
Monk ability: Unarmed Strike wrote:
A monk's attacks may be with fist, elbows, knees, and feet. This means that a monk may make unarmed strikes with his hands full.
This lets you use Quenching/Grounding/Neutralizing/Thawing to make your hands, feet, and head immune to [insert element] damage.
You can use Anchoring to make your limbs like immovable rods
2. That was all flavour text! You can make unarmed strikes at all times, because unarmed strikes are made when you aren't using a weapon to attack. This means that no matter how many unarmed strikes you make, you can still make more
[>2a. Your entire body is your weapon. This improves the above suggestions to 'your entire body is immune to [element] damage' and 'You can use Anchoring to make your body like an immovable rod' In addition, The Glamered or Transformative effect give you at-will disguise self or even let you transform into 'weapons of the same general shape and handedness' (That's Me, the giant club)
[>2b. None of your body is an unarmed strike. Unarmed Strikes use your natural reach, but since you can still make unarmed strikes if you are tied to a wall (no use of feet hands, or head), you can use the Throwing/Returning (or Call) combo for this. In fact, you don't even need the returning/call property