If it's not on the battlefield when the second card is drawn, the ability can't trigger at all that turn
With an Esper deck, you shouldnt be lacking in a library full of instants and sorceries to fuel your hate
Shanna lets you draw cards equal to the amount of life you gained on your turn as long as you pay for each of those cards
The main downside is that it comes in with Vanishing 3, so it will only stick around for a few turns before it gets sacrificed
Job select creatures will often trade with other job select cards, and Summons may also gum up the board
As such, it's probably not a surprise that the decks built around more evergreen themes like instants, Humans, or cycling crushed the decks that are basically Ikoria -block Commander decks without the best Ikoria cards