The two piece Ultimate Guard Boulder Deck Box certainly earns its rock-based name too, feeling like an absolute brick when its filled with cards
Being able to sacrifice merfolk to counter noncreature spells is very strong, especially when played with cards like Deeproot Waters that create merfolk tokens
This is especially true for cards that also make permanents, like Herd BalothHerd Baloth or Basking BroodscaleBasking Broodscale
Candelabra of tawnos: allowed you to abuse the powerful lands too easily (mishra's workshop and library of alexandria in particular)
Poor-quality tools introduce friction, increase wear, and slow down play
Technomancer is the workhorse: it enters, mills three, and returns any number of artifact creatures with total mana value six or less straight to the battlefield, so one card can rebuild half a board