In less graveyard-intensive decks, one or two escape cards should function perfectly fine by themselves
Niv-Mizzet Reborn literally resurrects as the manifestation of the Guildpact during the War of the Spark
As 99.9% of the cards in this game are different, the dialogue, trades and text in the game have also been altered to reflect that difference
The fact that these are permanents, which can potentially be flickered, reanimated, or otherwise reused at low cost, makes these already flashy cards very strong
5 Madame Null, Power Broker Legendary Creature Madame Null, Power Broker is a three-mana 1/3 legendary creature with deathtouch, but more importantly, whenever a creature you control enters, you may pay life equal to its power to place that many +1/+1 tokens on it
At minimum you'll be paying 3 mana to save your commander, draw and discard a card which feels like a fair deal for its mana cost and I can see many Dimir graveyard, discard, reanimator or Izzet/Grixis wheel deck slot this card for its instant speed potential