1) Flip the top card and it's a Path of Discovery.
1a) Diviner gets +1/+1
1b) Walker #1 triggers twice, getting +2/+2 and I gain 6 life.
1c) Walker #2 does the same.
1d) Ascendancy gets 10 tokens (5x2 because of Panharmonicon)
2) Repeat.
3) I chump with three Saproling tokens to stay alive.
4) I win the game on my next upkeep?
The only trigger that Panharmonicon doubles here is Diviner's "when enters the battlefield, explores".
Wildgrowth's and Ascendancy's abilities trigger from what happens when Diviner's ability resolves, not by Diviner entering itself, so their abilities trigger only once per exploration.
So, when Diviner enters, its explore ability triggers twice.
When the first exploration happens, each Wildgrowth triggers only once. If the revealed card is nonland, Ascendancy triggers once too.
Each Wildgrowth ability resolving causes Ascendancy to trigger once again.
After all this, you explore again, triggering the same things again.
Assuming you revealed a nonland twice (keeping it at the top the first time helps), Diviner gets two +1/+1 counters, each Wildgrowth gets two +1/+1 counters too, you gain a total of 12 life, and Ascendancy gets only 6 growth counters.
1) Flip the top card and it's a Path of Discovery.
1a) Diviner gets +1/+1
1b) Walker #1 triggers twice, getting +2/+2 and I gain 6 life.
1c) Walker #2 does the same.
1d) Ascendancy gets 10 tokens (5x2 because of Panharmonicon)
2) Repeat.
3) I chump with three Saproling tokens to stay alive.
4) I win the game on my next upkeep?
Wildgrowth's and Ascendancy's abilities trigger from what happens when Diviner's ability resolves, not by Diviner entering itself, so their abilities trigger only once per exploration.
So, when Diviner enters, its explore ability triggers twice.
When the first exploration happens, each Wildgrowth triggers only once. If the revealed card is nonland, Ascendancy triggers once too.
Each Wildgrowth ability resolving causes Ascendancy to trigger once again.
After all this, you explore again, triggering the same things again.
Assuming you revealed a nonland twice (keeping it at the top the first time helps), Diviner gets two +1/+1 counters, each Wildgrowth gets two +1/+1 counters too, you gain a total of 12 life, and Ascendancy gets only 6 growth counters.