Season of Loss

Choose up to five {P} worth of modes. You may choose the same mode more than once.
{P} — Each player sacrifices a creature of their choice.
{P}{P} — Draw a card for each creature that died under your control this turn.
{P}{P}{P} — Each opponent loses X life, where X is the number of creature cards in your graveyard.

Bloomburrow

Choose up to five {Paw Print} worth of modes. You may choose the same mode more than once.
{Paw Print} — Each player sacrifices a creature.
{Paw Print}{Paw Print} — Draw a card for each creature you controlled that died this turn.
{Paw Print}{Paw Print}{Paw Print} — Each opponent loses X life, where X is the number of creature cards in your graveyard.

Bloomburrow Promos

If a Season is copied, the effect that creates the copy will usually allow you to choose new targets, but you can't choose new modes.

If a mode requires a target, you can select that mode only if there's a legal target available. Ignore the targeting requirements for modes you don't choose. Each time you select that mode, you can choose a different target, or you can choose the same target.

If all targets for the chosen modes become illegal before the Season resolves, the spell won't resolve and none of its effects will happen. If at least one target is still legal, the spell will resolve but will have no effect on any illegal targets.

No matter which combination of modes you choose, you always follow the instructions of a Season in the order they are written. If the same mode is chosen more than once, you choose their relative order as you cast the spell.

No player can cast spells or activate abilities in between the modes of a resolving spell.

The pawprint symbol does not represent a cost, mana, counters, or any kind of persistent resource. You can't "save up" pawprint symbols from one Season spell to use on a future one, mostly because there isn't anything concrete to save up. They're just pawprints.

When you're following the instructions from the first mode, first the player whose turn it is chooses which creature they're going to sacrifice, then each other player in turn order does the same. Players will know the choices of previous players when making their choices. Then all chosen creatures are sacrificed by their controllers simultaneously. Repeat this process for each additional time the first mode was chosen.

You choose the modes as you cast the spell. Once modes are chosen, they can't be changed.

You don't have to choose modes that add up to exactly five pawprints. For example, you could choose the two pawprint mode twice and leave it at that. You could even choose no modes at all. You probably shouldn't, but you could.