They will always count the modified Power/Toughness, including the bonus or penalty from any counters or other external effects like Auras or Enchantments. I don't think any card looks at only the printed P/T on a creature in the Battlefield.
Creatures with Wither deal damage as -1/-1 counters instead of usual damage. So in the case of a creature with Power 3 and Wither, instead of dealing 3 damage to another creature, it will place three -1/-1 counters on it instead.
Toughness, yes, Power, no. If a creature's Toughness ever goes to zero or below, it is put into the graveyard. However reducing a creature's Power to zero or below, will do nothing, apart from make it unable to deal damage.
Giant Growth does not add counters. It only changes power and toughness for one turn and is not a permanent. Proliferate would not effect a creature who Giant Growth had been used on.
If ever a creature's toughness is reduced to zero (or less), it will be destroyed as a state-based effect. If a 1/1 creature gets a -1/-1 counter, then effectively it has a toughness of zero, and will be destroyed. Edit: Note that a creature having 0 toughness is not a destroy effect. As per the state based actions, it will be put into its owner's graveyard. This does trigger "Dying" effects. This is an important distinction as having 0 toughness is one of the ways to get rid of indestructible creatures.
there is no invincible ability; however, there's an indestructible: it means if it's a creature, lethal damage or "destroy" effects don't kill it. note that if something is indestructible, it can still be sacrificed and it will die. If it gains -1/-1 counters greta than or equal to it's toughness, it also dies.
The artifact creature 'Pentavus' can remove its +1/+1 counters to create 1/1 flying Pentavite tokens.
There is no best card. It all depends on how you play and your preferences. In terms of power and toughness, it's the 13/13 Krosan Cloudscraper.
Yes. When a creature has both -1/-1 counters and +1/+1 counters, you remove one of each until the card has only one kind. So if a creature had 3 -1/-1 counters on it, and an ability placed 2 +1/+1 counters on it, you would remove 2 of the +1/+1 counters and 2 -1/-1 counters, so it remains with only one -1/-1 counter. This action is a state-based action. If anyone would like to see this ruling in the Magic Comprehensive rules, you may find it at 120.2
Ki counters are simply regular counters that most commonly apply to spirit or arcane cards. For example, a card may say: Whenever another spirit creature comes into play, put a ki counter on "this card", remove two ki counters from "this card" put a 1/1 spirit creature token into play. This is just one example, ki counters are mostly accumulated from spirit or arcane cards and have a variety of different effects.
The number that appears to the left of the "/" is the creature's power, aka it's attack.The number to the right is it's toughness, aka it's defense.For example, for a 5/3 monster, 5 is it's power and 3 is it's toughness.
The "pt" in deck building typically stands for "power and toughness." It refers to the numerical values that represent a creature card's strength and durability in games like Magic: The Gathering. Power represents the amount of damage the creature can deal, while toughness represents the amount of damage it can withstand before being destroyed.
Creature: rat ninja Mana cost:4B Abilities:Ninjutsu 2B, Whenever Throat Slitter deals combat damage to a player destroy target nonblack creature that player controls Power:2 Toughness:2