Platinum Angel was probably the next card on the list, and it argued that it prevented you from losing the game, but I still say better luck on the next ballot
Similarly, if the Mayor is blocked by a 2/2 with first strike, he will die before your other 2 humans get to deal damage in the second damage step, where they will just be 2/2s again
For the occasional removal of artifacts or enchantments, I will give preference to an Acidic Slime over a Nature's Claim
While its technically possible to give a player poison counters directly (Caress of Phyrexia comes to mind), the most popular poison counters strategy involves running a bunch of infect or toxic creatures
This, partnered with the Sabrina Trainer card, will have the player questioning their next move