Eles não empilharam

Do SRD :

Combining Magical Effects

The effects of different spells add together while the durations of those spells overlap. The effects of the same spell cast multiple times don’t combine, however. Instead, the most potent effect—such as the highest bonus—from those castings applies while their durations overlap.

For example, if two clerics cast bless on the same target, that character gains the spell’s benefit only once; he or she doesn’t get to roll two bonus dice.

Embora o dano de Ray of Frost seja aplicado a cada acerto, a redução de velocidade é um efeito que a regra acima impediria de empilhar consigo mesma. No entanto, ainda seria empilhado com outros redutores de velocidade, como Lance of Lethargy ou Frost Lance .

Você não pode empilhar efeitos mágicos idênticos

Os Regras básicas afirmam:

The effects of different spells add together while the durations of those spells overlap. The effects of the same spell cast multiple times don't combine, however. Instead, the most potent effect — such as the highest bonus — from those castings applies while their durations overlap.