Magic: The Gathering Universes Beyond: Warhammer 40,000 Collector's Edition Commander Decks
Terror of the Peaks can deal a lot of damage when you escape that Ox of Agonas, and triggering your Chulane, Teller of Tales twice with Uro, Titan of Nature's Wrath feels disgusting
If you see that someone owns four Fable tokens (~$8/card), youll think to yourself: Man, they really love Fable of the Mirror-Breaker
And this is doubly true since by increasing supply, Secret Lair reprints tend to reduce the value of the older, cheaper versions of the cards featured in the drops, potentially allowing you to pick up less desirable (but just as playable) versions at a discount
If you want to learn more about advanced tactics in sideboarding, I recommend checking out this course on Spikes Academy
The other huge upgrade that isn't a Vampire is, of course, Skullclamp, which if you're lucky enough to find / stick on the battlefield will draw you all the cards you need to close out the game