Hatchery Sliver + Memnite + Leyline of Transformation

Hatchery Sliver

Memnite

Leyline of Transformation

How it works

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