Power of All question

Can you play Power of All to cancel a reaction card or a master card during your own action when acting on someone else's turn via Enkil Cog or Madness Network? Power of All Requires a ready anarch. Tap this anarch and one other untapped ready anarch you control to cancel a library card as it is played. Usable even if there is no action. Not usable during your own turn.

I don't think so. It's still a reaction card, so you cannot play it while one of your minion is acting. My guess us that the clause "Not usable during your own turn." is there to prevent that you're able to cancel a SR/Wash that is played during your master phase.

You cannot play reaction cards if you control the acting minion (Rulebook 1.6.3.6). Ralf got it faster than me.