Pauper would greatly benefit from the following cards:
Rust
Remove Enchantment
The first one is probably the one with the most potential in the current metagame. It did see play in tabletop, as it is a good way to address graveyard hate from cards like Nihil Spellbomb and Relic of Progenitus.
The second one also saw play in tabletop, albeit the meta now doesn't need such an aswer as much as it may've needed in the past. The card is a good way to deal with Auras deck like Bogles Hexproof and White Heroic.
There is also cards missing from MTGO, like Equinox, but that likely wouldn't see that much play... But the other two I mention are definitely good additions choices for the online metagame
