Copy Sporecrown Thallid and Tendershoot Dryad and protect them with Hexproof to get giant Saprolings.
(I still need more Metamorphic Alteration, Quasiduplicate, Mirror Image, Helm of the Host)

//Update 23.01.2019

Creatures (14):
4x Llanowar Elves
2x Elfhame Druid
4x Sporecrown Thallid
4x Tendershoot Dryad

Non-creature Spells (22):
3x Verdant Rebirth
4x Dive Down
2x Curator's Ward

2x Metamorphic Alteration
3x Quasiduplicate

2x Path of Discovery
4x Saproling Migration
4x Spore Swarm

Lands (23):
9 Forest
6 Island
1 Memorial to Unity
2 Memorial to Genius
4 Woodland Stream
1 Hinterland Harbor

Sounds a bit too cute - hexproof is not sufficient because sweepers still kill them.

Why not run recursion instead? Basically, port the BG Saprolings deck from Dominaria draft to constructed.

The simple answer is.. it's not a T1 deck, it's just a fun theme deck.

If you wanna get serious with it you could add some counter spells, or you go BG which probably does it better.