I like to second the praise for Phyrexian Totem, it has won me several games against opposing walkers AND provides black mana when needed. Very strong option, which gets overlooked a lot. I also play 2 Phyrexian Arena, but as stated before this is mainly due to a lack of Karn, which in theory appears stronger.
I don't like Night's Whisper in Pox. It's OK to hit land drops early game, but for 2 mana (and 2 life) I would rather play disruption or drop a permanent. Arena just feels stronger for 1 more mana, and requires removal or provides a game winning advantage.
Also, while I understand that Pox needs to be metagamed and has lots of viable options, we are far away from a common stock list. I still would like some opinions on the following points:
- Dark Ritual, yes or no? I think yes, required for explosive starts and to overcome mid-game lack of black sources
- Card draw, yes or no? I think yes, drawing off the top without card selection kills us in the long run, every time (competent Jace players will always use the fateseal on us, and it's usually game). A black Mirri's Guile would be the perfect solution
- Sinkhole, yes or no? I think no. I really like the card, it sometimes wins games in the first few turns, but most of the time it never seals the deal and most deck simply draw more than enough mana (cantrips, library manipulation, mana dorks, draw effects)
- Delve creatures, yes or no? Standard lists run Nether Spirit, Factories and Scrolls. While non-recurring creatures are anti-synergistic with our strategy, several decks are in severe trouble once a Tombstalker or Fiend hits the table. They are fast evasive clocks and dodge mana cost based removal