Pretty much every warrior hates to be rooted in place not being able to react. Even if it procs Second Wind...
Here's the macro :
/Equip slot 17 [button:1] <Your shield here>
/Equip slot 16 [button:1] <Your 1h here>
/cast [stance:1/3]Defensive Stance
/cast Bloodrage (If you don't have Tactical Mastery)
/cast Spell Reflection
/Equip slot 16 [button:2] <Your 2h here>
If you're using 2 1h weapons, go respec! Kidding, swap the 2h part with this :
/Equip slot 17 [button:1] <Your shield here>
/Equip slot 16 [button:2] <Your 1h here>
If you're using the same weapon with your shield and with your offhand, you can remove the parts that say "equip Mainhand" and "equip 1h".
How it works:
Left clicking on this macro will immediately equip your shield (first) and your weapon (second) while changing to Battle Stance (that is, if you are in Berserker Stance). The scripts in that macro wont allow you to do errors with it, such as using it in defensive stance or stance dancing battle to battle by accident with rage lost. With your shield equipped right away and being ready in battle stance, you could use Spell Reflection immediately. If you just stance danced and you don't have tactical mastery, Blood Rage could be needed. Only 1 click is needed on that macro, and once it's acted, simply use Spell Reflection (I keep it right besides that macro, so i don't need to search far for it). When you just got either Rooted, Imp Hamstring, Imp Wing Clip or Frost Nova (including Frost Bite) When you want to annoy those freaking PoM-Pyro mages.
RIGHT clicking on that macro will re-equip your regular DPS weapon(s). This is why the "button:1/2" are in the scripts. It might be hard to master at first, but patience will make it worth.
Best used when: you know you are going to get spell casted and you can't interupt it (Cyclone, Sheep, or even just a regular spell).