Penance is the second upgrade
This is easier to help accumulate poison counters than attacking for infect damage with the potential of your opponent blocking your attack with a creature they control
Probably, they are looking to sell the cards they don't need from draft or sealed
Cards like [card]Glistener Seer[/card], [card]Bellowing Crier[/card], and [card]Pod Prophet[/card] help support the plan, though [card]Pond Prophet[/card] is probably the only one thats somewhat playable outside of this deck
For instance, the Azgol and Tarkir invasions are removal spells that can kill opposing creatures on sight, whereas the Ixalan and Pyrulea invasions let you look at the top few cards of your library and draw one of them
However, its lack of special effects means its susceptible to enemy Traps, which means players may want to ensure Meteor B