Faith's Fetters
Enchantment — Aura
Enchant permanent
When Faith's Fetters enters, you gain 4 life.
Enchanted permanent can't attack or block, and its activated abilities can't be activated unless they're mana abilities.
Illustrated by
Foundations Jumpstart#195CommonEnglishLegality
Rulings
If the target permanent is an illegal target by the time Faith’s Fetters tries to resolve, it doesn’t resolve. It won’t enter the battlefield, so its enters-the-battlefield ability won’t trigger.
Activated abilities contain a colon. They’re generally written “[Cost]: [Effect].” Some keywords (such as equip) are activated abilities and will have colons in their reminder text. Loyalty abilities of planeswalkers are activated abilities.
Faith’s Fetters doesn’t stop static abilities, triggered abilities, or mana abilities from working. A mana ability is an ability that produces mana, not an ability that costs mana.