Hatchery Sliver + Maskwood Nexus + Kobolds of Kher Keep

Hatchery Sliver

Maskwood Nexus

Kobolds of Kher Keep

How it works

1. Cast Kobolds of Kher Keep by paying 0, and choosing to pay its replicate cost an arbitrarily large number of times by paying 0.
2. Kobolds of Kher Keep triggers, creating a copy of it for each time its replicate cost was paid.
3. Resolve all Kobolds of Kher Keep spells, causing the nontoken Kobolds of Kher Keep to enter the battlefield, and creating a token copy of it for each time its replicate cost was paid.

This delightful engine turns the humble, free casting cost of Kobolds of Kher Keep into an overwhelming swarm of creatures by leveraging the blanket type-granting effect of Maskwood Nexus. Because Maskwood Nexus makes every creature you control, creature spell, and creature card in your hand a Sliver, Hatchery Sliver's static ability reaches out to grant its replicate keyword to your free creature spells. This allows you to pump an arbitrary amount of mana into copying Kobolds of Kher Keep over and over again, flooding the board with an endless army of tokens and entering-the-battlefield triggers for practically nothing.