Worms of the Earth — ruling 1

If a permanent spell tries to enter as a land during its resolution (for instance, a Clone entering the battlefield as a copy of a Dryad Arbor or an animated Mutavault), it is put into its owner's graveyard instead of entering. It never enters, so abilities that would have triggered on it entering won't trigger.

Worms of the Earth — ruling 2

In Two-Headed Giant, triggers only once per upkeep, not once for each player.

Worms of the Earth — ruling 3

Land can't enter, so an effect that "puts a land onto the battlefield" won't do anything, and the land will stay where it is.

Worms of the Earth — ruling 4

If you cast a spell or activate an ability that lets you put a land onto the battlefield, the effect fails. You'll still do everything else the spell or ability tells you to do, such as shuffle the library.

Worms of the Earth : règles, fonctionnement et interactions (MTG)

Worms of the Earth is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Players can't play lands. Lands can't enter the battlefield. At the beginning of each upkeep, any player may sacrifice two lands of their choice or have this enchantment deal 5 damage to that player. If a player does either, destroy this enchantment.

How it works : Worms of the Earth

Original English text — Wizards of the Coast / Scryfall

#1August 1, 2008· Wizards of the Coast
If a permanent spell tries to enter as a land during its resolution (for instance, a Clone entering the battlefield as a copy of a Dryad Arbor or an animated Mutavault), it is put into its owner's graveyard instead of entering. It never enters, so abilities that would have triggered on it entering won't trigger.
No other card is named in this ruling.
#2May 1, 2006· Wizards of the Coast
In Two-Headed Giant, triggers only once per upkeep, not once for each player.
No other card is named in this ruling.
#3October 4, 2004· Wizards of the Coast
Land can't enter, so an effect that "puts a land onto the battlefield" won't do anything, and the land will stay where it is.
No other card is named in this ruling.
#4October 4, 2004· Wizards of the Coast
If you cast a spell or activate an ability that lets you put a land onto the battlefield, the effect fails. You'll still do everything else the spell or ability tells you to do, such as shuffle the library.
No other card is named in this ruling.