when a creature leaves play and returns to play does it restart its effects

[Piplup]

when a creature leaves play and returns to play does it restart its effects

[Kenji]

You're going to have to be more specific than that, because the way you asked that question is incredibly vague.

Do you have any particular creatures in mind? If you give us some examples, we can provide you with a more comprehensive answer.

Here, I'll guess at what you're trying to ask. If you meant something else entirely, feel free to correct me:

"when a creature leaves the battlefield and returns to the battlefield, and it has an "enters-the-battlefield" triggered ability (Centaur Healer, for example), does that ability trigger again?"

If that's what you meant, the answer is "yes." Enters-the-battlefield triggered abilities will trigger whenever the creature in question enters the battlefield from anywhere else.

[Piplup]

Karstoderm

[Kenji]

Ah, okay. I can answer that for ya. Straight from the Comprehensive Rules:

400.7. An object that moves from one zone to another becomes a new object with no memory of, or
relation to, its previous existence. There are seven exceptions to this rule:

None of the exceptions apply here, so there's no need to quote those. Anyway, if Karstoderm leaves the battlefield and returns to the battlefield via something like Cloudshift, it loses whatever +1/+1 counters it had previously. As it's entering the battlefield, it will have its initial five +1/+1 counters on it once again.

Oh, this rule is also relevant:

121.2. Counters on an object are not retained if that object moves from one zone to another. The
counters are not “removed”; they simply cease to exist. See rule 400.7.

So, the counters that Karstoderm had on it cease to exist in that brief moment when it is exiled. Then, upon entering the battlefield again, it will have five +1/+1 counters on it, since that's always how it enters the battlefield according to its ability.