Why Destructive Salutation and not Sleep? That's the one that was pounced on the day after 4E's release....
(One house rule I've seen is that penalties to saves don't stack. That serves to cut down on this cheese quite handily.)
This is one of those combos... wow...
It can be used once, maybe twice, per day. It is not a game breaker unless the DM literally only uses 1 encounter per day, and then, only if there is a single vastly important entity involved in that fight. If the DM builds encounters like I do, then usually there are no "OMG! Kill it!!" creatures involved. Instead, there is a team of enemies working together to end the PC's lives, or capture them at least.
Also, this tactic does absolutely nothing when the only encounters the PC's face in a given week is social encounters, lol... The game isn't always about combat.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.