Bahamuts Breath

You touch one willing creature and imbue it with the power to spew magical energy from its mouth, provided it has one. Choose Repulsion, Sleep, Paralysing, Slowing or Weakening. Until the spell ends, the creature can use an action to exhale an effect of the chosen type in a 15-foot cone. Each creature in that area must make a saving throw from the below descriptions or take the effect described. On a successful save the creature is not affected and has advantage on any further checks to resist.

Repulsion - Make a STR saving throw or be pushed back 10 feet.

Sleep - Make a CON save or become unconscious for 10 minutes. This effect is undone if the creature takes damage or another creature uses an action to wake them.

Paralysing - Make a CON saving throw or be paralysed for 1 minute. A creature can make a save against this effect at the end of their turn. 

Slowing -  Make CON saving throw. On a failed save, the creature can't use reactions, its speed is halved, and it can't make more than one attack on its turn. In addition, the creature can use either an action or a bonus action on its turn, but not both. These effects last for 1 minute. The creature can repeat the saving throw at the end of each of its turns, ending the effect on itself with a successful save.

Weakening - Make a STR saving throw or take disadvantage on str weapon attacks, checks and saving throws for 1 minute. A creature can save against this affect at the end of their turn.