If another effect (or effects) modifies how much damage a source would deal to the chosen player or a permanent they control (for example, by preventing some of that damage), the player being dealt damage or the controller of the permanent being dealt damage chooses the order in which any such effects, including the effect of Sawhorn Nemesis, apply
Check your old cards against the factors covered here, and you may be surprised by whats sitting in a binder
For Kelsien you'd want ways to give her deathtouch with Basilisk Collar or a few other ways and then equip Thornbite Staff
It That Betrays was an awesome reprint, and I recently managed to find one myself to put in my Eldrazi Incursion upgrade (more on that later)
Four mana on Turn 1 or five mana on Turn 2, Jeweled Lotus can power out a higher cost Commander way ahead of curve
That would make this Black Lotus the second most expensive MTG card ever sold - except that Post Malone recently claimed to have bought a similar Black Lotus for $800,000