Day of the Triffids

All Forests and all Saprolings are 1/1 green Saproling creatures and Forest lands in addition to their other types. (They're affected by summoning sickness.)

As this enchantment enters, choose a creature type. Each creature you control is the chosen type in addition to its other types.

When this creature enters, create a 0/1 green Plant creature token for each land you control. Landfall — Whenever a land you control enters, you may put a +1/+1 counter on each Plant creature you control.