Was doing a search for Tethra’s Doom on the Warframe site today (I was in a really boring meeting at the time.) Search results yielded the following info –

All These primes were added in 12.4 with Tethra’s Doom

  • Rhino Prime
  • Ankyros Prime
  • Boltor Prime
  • AkBronco Prime
We will get updates thru 12.4.4 with Cherry Picked Frost changes.
You can expect these in the next update.
Looks rather sweet to me. From comments made by the PC side who participated, the event appeared to be pretty easy and did not take a lot of grinding to accomplish the event stages. Earning 500 points paid off in four new mods, the Gorgon Wraith weapon and other rewards.
I’m sure Lotus will appraise everyone of the total picture when the time comes.