Sabotender slots nicely into Rakdos Aggro as far as colors go, but costing 1 more mana than Iridescent Vinelasher is not nothing: red and black both have tons of good options at 2, from mice to Cori-Steel Cutter, and none of the colors play extra land drops
Just be sure to pack extra sleeves and deck boxes to protect your Forces
Seven mana is a lot, but so, so worth it to play this unholy avatar of blue
Its especially good if you have ways to benefit from other players sacrificing creatures
Attendees could gain non-foil versions of these cards by participating in side events like Pack Rush," while more limited foil variants were exclusive for prizes in the main challenge
You're less likely to run out of spells to play, and more likely to have an answer to an opponent's threat