Eldrazi Tron is a colorless/artifact ramp deck built around Urza lands, Expedition Map, and Karn, the Great Creator, making Meltdown a powerful sweeper against their cheap artifacts like Expedition Map and Talisman of Resilience at a low X. Tormod's Crypt is a cheap, narrow answer to their graveyard recursion like Abstergo Entertainment, and it costs almost nothing to hold. Mutagenic Growth is the weakest card here since their deck has few creatures worth trading with early (Devourer of Destiny and Ulamog are far too large for a pump to matter), and their removal (Dismember) kills our small creatures through a pump anyway. Race them before Karn shuts off the activated abilities of our artifacts and Ugin exiles our colored permanents.