Vanquish is going to be a WW Day of Judgment nearly every time you want to cast it, since 6 creatures is around the time you'd start considering casting a wipe
It then becomes a 0/0 Phyrexian creature and you can attack and block as normal (summoning sickness applies)
The only thing you might do differently in the year ahead is to cull some of the lower powered energy cards to add more protection spells and countermagic, because players will learn that Satya is a must-kill on sight
The flip condition seems fair: play two Spirits or Arcanes, collect two ki counters, then flip
Or, if you want to check out your options when it comes to Commanders using only those from the Lord of the Rings MTG set, check out our list of all LOTR MTG Commanders.
The activated ability isnt the focus, but its a nice touch