Phased out creatures still get counters from conniving
How to reproduce/sequence that triggered this problem:
Alice plays Ledger Shredder
Bob casts a spell
Alice casts a counterspell
Ledger Shredder's ability triggers and goes on the stack
Bob casts a counterspell targeting Alice's counterspell
Ledger Shredder's ability triggers and goes on the stack
Bob casts March of Swirling Mist to phase out Ledger Shredder before the connive triggers resolve
MoSM resolves, Ledger Shredder phases out
Ledger Shredder connive trigger resolves twice as the stack pops down
Alice discards a nonland card both times
Platform: PC
Actual result:
Ledger Shredder, though phased out, still gets a +1/+1 counter both times
Expected result:
Ledger Shredder is phased out, and does not exist. It should not be possible for it to have counters placed on it. Per a ruling from 4/29/2022:
If a resolving spell or ability instructs a specific creature to connive but that creature has left the battlefield, the creature still connives. If you discard a nonland card this way, you won't put a +1/+1 counter on anything. Abilities that trigger “when [that creature] connives” will trigger.
Though this doesn't address the specific case of phasing, it seems the intended interaction is that Alice would still loot twice, but Ledger Shredder would not get any counters, regardless of which cards are discarded.