Eldrazi floods the board with colorless creatures like Eldrazi Linebreaker (3/3), Glaring Fleshraker (2/2), and Thought-Knot Seer (4/4). Massacre's -2/-2 sweeps away their Spawn/Scion tokens and the 2-toughness creatures, while Reality Smasher and bigger threats survive but get shrunk enough to matter in combat. Surgical Extraction is a flexible answer once a key creature such as Thought-Knot Seer has hit their graveyard, since it exiles the remaining copies from their hand and library as well. It costs only 2 life, so it doesn't tax our mana. Collective Brutality's -2/-2 mode is largely redundant with Massacre, and its discard mode can only hit instants and sorceries, which in this matchup means little more than Kozilek's Command and Eldrazi Confluence, so it comes out. Unmask is also cut: exiling a black card from hand to cast it is card disadvantage, and paying its full cost is too slow against a deck that just wants to curve out. Watch out for Chalice of the Void set to one, which counters our mana value 1 spells like Dark Ritual, Thoughtseize, and Reanimate. Lotus Petal has mana value 0 and is unaffected by a Chalice on one, but a Chalice on zero would stop it. Sequence around Chalice when possible.