Can you use negate on a Planeswalker?

Yes, Planeswalkers are not creature (and there is no card typed Planeswalker Creature so far) so they all can be countered by Negate.

Is summoning a Planeswalker a spell?

“Planeswalkers” as such are permanents on the battlefield (C.R. 109.2), not spells or players (compare C.R. 110.1 with C.R. 111.1 and 102.1).

Can you cast creature abilities during opponent’s turn?

Yes and yes. Activated abilities can be activated on an opponent’s turn (provided it’s not explicitly disallowed for that specific ability), whenever you could cast an instant spell.

When can you use creature abilities?

Also, you can usually activate an activated ability any time you have priority, unless it says otherwise. Except for those that are mana abilities, activated abilities use the stack. ) in its cost unless they have controlled the creature continuously since the start of their most recent turn.

Can you activate mana abilities as instants?

605.5b. A spell can never be a mana ability, even if it could put mana into a player’s mana pool when it resolves. It’s cast and resolves just like any other spell. Some older cards were printed with the card type “mana source”; these cards have received errata in the Oracle card reference and are now instants.

Can you activate abilities before upkeep?

Upkeep Step – This happens directly after untap and is the first time players may take action during a turn. Abilities that trigger at the beginning of upkeep go on the stack, and then players can play instants and abilities. Once that is done, both players may play spells and abilities.

When can you activate artifact abilities?

Activated abilities of permanents can be activated at any time you could play an instant, unless something says otherwise. Abilities of noncreature permanents (including noncreature artifacts) can be activated the turn they enter the battlefield. Only creatures are subject to “summoning sickness.”

Is an interrupt an instant?

Interrupt is an obsolete card type. Some examples of interrupts include Counterspell, Red Elemental Blast, and Dark Ritual. All interrupt cards have received errata to make them instants, and all references to interrupts have been given errata to reference instants instead.