## Any saving throw against any spell you cast, no matter when the spell was cast.

For a target to have disadvantage against a saving throw, the following conditions must be met:

*  the hound is within 5 feet of the target
* The saving throw is against the effect of a spell that you cast

These are the conditions. Let us examine several scenarios. Assume the hound is within 5 feet of the target at all times. 

### Spell cast anytime in the past, new saving throw against the effect.

Say we cast *hold person* on the target last turn. The target then ends its turn with our hound next to them. *Hold person* calls for a wisdom save. Let's check our conditions:

* The hound is within five feet of the target.
* *Hold person* is a spell that we cast. 

Therefore the target has disadvantage on the wisdom save. 

### Spell cast on our turn.

Say we cast *hold person* this turn while our hound is within five feet of the target. Let's check our conditions:

* The hound is within five feet of the target.
* *Hold person* is a spell that we cast. 

Therefore the target has disadvantage on the wisdom save. 

### Spell cast on the target's turn.

Say the target attacks us while our hound is within five feet of the target. We use our reaction to cast *hellish rebuke*. Let's check our conditions:

* The hound is within five feet of the target.
* *Hellish rebuke* is a spell that we cast. 

Therefore the target would have disadvantage on the dexterity save.

### You cast the spell a month ago.

Suppose we have taken the Keen Mind feat and know exactly what time it is at all times. We cast *feeblemind* on the target and they fail their save. Exactly 30 days later, we conjure our hound and place the hound within five feet of the target. *Feeblemind* says:

>At the end of every 30 days, the creature can repeat its saving throw against this spell. 

Let's check our conditions:

* The hound is within five feet of the target.
* *Feeblemind* is a spell that we cast. 

Therefore the target would have disadvantage against the intelligence save. 

Okay, this one may seem a little silly, and a DM may rule that there are some problems with lining up the five minutes of your hound with exactly 30 days after you initially cast *feeblemind*. But it is an important example because of the language it uses. Notice what it says:

>the creature can repeat its saving throw *against this spell*.

**Saving throws against spell effects for spells that were cast in the past are still saving throws against the spell**. 

Therefore, when Hound of Ill Omen says "the target has disadvantage on saving throws against any spell you cast", this includes saving throws against spells that are made in the future.