Collective Restraint
Enchantment
Domain — Creatures can't attack you unless their controller pays 
for each creature they control that's attacking you, where X is the number of basic land types among lands you control.
Alan Rabinowitz
The List (PLST)
• #INV-49Rulings
The basic land types are Plains, Island, Swamp, Mountain, and Forest. Land types other than basic land types (such as Desert) don't contribute to domain abilities.
(wotc • 2021-06-18)
Domain abilities count the number of basic land types among lands you control, not how many lands you control or how many of any type.
(wotc • 2021-06-18)
Unless some effect explicitly says otherwise, a creature that can't attack you can still attack a planeswalker you control.
(wotc • 2014-02-01)
In the Two-Headed Giant format, you still only have to pay once per creature.
(wotc • 2007-02-01)
Rulings
The basic land types are Plains, Island, Swamp, Mountain, and Forest. Land types other than basic land types (such as Desert) don't contribute to domain abilities.
(wotc • 2021-06-18)
Domain abilities count the number of basic land types among lands you control, not how many lands you control or how many of any type.
(wotc • 2021-06-18)
Unless some effect explicitly says otherwise, a creature that can't attack you can still attack a planeswalker you control.
(wotc • 2014-02-01)
In the Two-Headed Giant format, you still only have to pay once per creature.
(wotc • 2007-02-01)