606. Loyalty Abilities
In short
Loyalty abilities of planeswalkers: only at times you could cast a sorcery, and only ONE per planeswalker per turn. The loyalty cost (+N/−N) is part of the cost — an ability with −7 can only be activated if enough counters are on it.
Informal summary — the official English text below is authoritative.
606.1.Some activated abilities are loyalty abilities, which are subject to special rules.
606.2.An activated ability with a loyalty symbol in its cost is a loyalty ability. Normally, only planeswalkers have loyalty abilities.
606.3.A player may activate a loyalty ability of a permanent they control any time they have priority and the stack is empty during a main phase of their turn, but only if no player has previously activated a loyalty ability of that permanent that turn.
606.4.The cost to activate a loyalty ability of a permanent is to put on or remove from that permanent a certain number of loyalty counters, as shown by the loyalty symbol in the ability’s cost. This cost may be modified by other effects.
606.5.If the total cost to activate a loyalty ability contains multiple costs to add or remove loyalty counters, those costs are combined into a single cost to add or remove loyalty counters, as appropriate.
Example: A player controls Carth the Lion, which says, in part, “Planeswalkers’ loyalty abilities you control cost an additional [+1] to activate. That player also controls a planeswalker with three loyalty counters. To activate one of that planeswalker’s abilities that normally costs [+1], they put two loyalty counters on it. To activate one of its abilities that normally costs [−4], they remove three loyalty counters from it.
606.6.A loyalty ability with a negative loyalty cost, taking into account any additional costs, can’t be activated unless the permanent has at least that many loyalty counters on it.
Source: Wizards of the Coast, Magic: The Gathering Comprehensive Rules. Unofficial presentation under the Fan Content Policy. Rules effective as of Sep 25, 2026