Does a planeswalker's loyalty ability go on the stack and can it be countered?

Loyalty abilities are a special type of activated ability found on planeswalkers. When you activate a loyalty ability, it is placed on the stack just like any other activated ability (CR 602.2). This means opponents have the opportunity to respond before it resolves.

Because loyalty abilities use the stack, they can be countered by any spell or effect that specifically counters activated abilities, such as Stifle or Disallow (CR 602.2a). Note that generic counterspells like Counterspell only counter spells, not activated abilities, so they cannot counter a loyalty ability.

There are strict timing rules around loyalty abilities: you may only activate one loyalty ability of a given planeswalker per turn, and only during your main phase when the stack is empty (CR 606.3). The loyalty cost (adding or removing counters) is paid immediately when you activate the ability, not when it resolves (CR 606.3). So even if the ability is countered, the loyalty counters are already spent.

Example: You activate Chandra, Torch of Defiance's +1 loyalty ability. Your opponent responds with Stifle, countering the activated ability. The ability never resolves, but Chandra still has the +1 loyalty counter added because the cost was paid on activation.

• Generic counterspells (e.g., Counterspell) — cannot counter loyalty abilities
• Activated-ability counters (e.g., Stifle, Disallow) — can counter loyalty abilities