Casting Hangarback Walker for 0, and it will enter the battlefield with zero +1/+1 counters. Since Hardened Scales requires “one or more” +1/+1 counters to be put on the permanent to trigger the replacement effect, Hardened Scales won’t trigger.

Does Hardened Scales stack?

Yes. Both effects will modify the act of placing one counter, and you will place 3 counters instead.

Does Hardened Scales trigger when moving counters?

Does Hardened Scales trigger when moving counters after Servant of the Scales dies? Yes, it does since you are placing counters on a creature.

Can you sacrifice a 0 0 creature?

No, you don’t have the opportunity to sacrifice that goblin. Every time someone would receive priority, just beforehand, state based actions are checked and carried out. One of these state based actions is: 704.5f If a creature has toughness 0 or less, it’s put into its owner’s graveyard.

Is hardened scales a triggered ability?

Note that Scales doesn’t have a triggered ability, but rather a static ability with a replacement effect: those don’t use the stack and behave very differently.

Does doubling season use the stack?

The replacement effects of Parallel Lives and Doubling Season are identical for tokens. They will stack, because you apply the replacement effects in any order.

Does moving counters count as putting them on?

121.5. If an effect says to “move” a counter, it means to take that counter from the object it’s currently on and put it onto a second object. If the first and second objects are the same object, nothing happens. If the first object has no counters, nothing happens; the second object doesn’t get a counter put on it.

Why did they ban cauldron familiar?

Perhaps the most unexpected ban in today’s surprise announcement was given to Cauldron Familiar, a common from Throne of Eldraine. Wizards is therefore banning Cauldron Familiar in order to “weaken these sacrifice strategies, open up more metagame diversity, and create a more fun gameplay environment.”

Why was Teferi banned?

The decision to ban these cards came from concerns that combo-based decks had become too powerful in Pioneer. After seeing a decline in players on Magic: The Gathering Online, Wizards of the Coast wanted to reduce the chances of players losing early on into a game.