Sand Strangler — ruling 1

If an ability checks whether you control a Desert or there is a Desert card in your graveyard, having more than one doesn’t matter. Controlling one is the same as controlling five. There is also no extra bonus for both controlling one and having one in your graveyard.

Sand Strangler — ruling 2

For abilities that trigger only if you control a Desert or there is a Desert card in your graveyard, one condition must be true as the ability triggers and one must be true as the ability resolves. They don’t have to be the same condition, though. For example, you could sacrifice your only Desert after the ability triggers but before it has resolved.

Sand Strangler : règles, fonctionnement et interactions (MTG)

Sand Strangler 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

When this creature enters, if you control a Desert or there is a Desert card in your graveyard, you may have this creature deal 3 damage to target creature.

How it works : Sand Strangler

Original English text — Wizards of the Coast / Scryfall

#1July 14, 2017· Wizards of the Coast
If an ability checks whether you control a Desert or there is a Desert card in your graveyard, having more than one doesn’t matter. Controlling one is the same as controlling five. There is also no extra bonus for both controlling one and having one in your graveyard.
No other card is named in this ruling.
#2July 14, 2017· Wizards of the Coast
For abilities that trigger only if you control a Desert or there is a Desert card in your graveyard, one condition must be true as the ability triggers and one must be true as the ability resolves. They don’t have to be the same condition, though. For example, you could sacrifice your only Desert after the ability triggers but before it has resolved.
No other card is named in this ruling.