Apologies if this is the wrong place to post this.
If I have a Hardened Scales and an Ozolith, the Shattered Spire on the battlefield and I cast a spell that causes a creature to get a +1/+1 counter, do I add a total of three +1/+1 counters to that creature or four?
In other words, do Hardened Scales and Ozolith, the Shattered Spire both see the new +1/+1 counter on the stack simultaneously and add a single additional +1/+1 counter each? Or would (for example) Hardened Scales see the original +1/+1 counter, and add another one to the stack, at which point Ozolith, the Shattered Spire sees the original +1/+1 counter and adds an additional counter to the stack, and then as a separate event sees the +1/+1 counter from Hardened Scales and adds a second additional +1/+1 counter?
If the latter is true, then adding a couple other cards (like a Pir, Imaginative Rascal and Kami of Whispered Hopes) would make this insane. Hardened scales adds 1 additional +1/+1, Ozolith, the Shattered Spire adds 2 more, then Pir adds 3, then Kami of Whispered Hopes adds 4, for a total of 11 (including the original +1/+1 counter).
It’s a replacement effect, adding one more counter to the existing effect, not creating a new effect that adds an additional counter. Keywords here are “if” and “instead”.
TL;DR - 3 Counters, not 4
+1
With replacement effects the affected player chooses which of all applicable replacement effects to apply first, then after applying that they check if any others need to be applied. Once there are no more applicable replacement effects the modified effect happens.
Thank you! I wasn’t thinking of it as a replacement effect, but that makes it very clear.