The optional press can only be used during the current round.
100376
Cold Aura
Only usable before range is determined.
Set the range for this round to long.
As above, with 1 optional press, only usable to end combat.
Rulings
Once the range is set, no other effect can be used to reset the range that round, but other pre-range effects can be played afterwards. Skip the Determine Range step for that round.
If another effect was already setting that round's range (e.g. Neutral Guard), that effect has priority.