I shall never be satiated. It doesn't sleep, it keeps eating until nothing is left. It can eat anything, even magic and use it to regain it's hit points. If it doesn't eat anything in 1 week, it will begin to eat itself.

I shall let my fangs do the talking. All attacks this creature's make are magical for the purpose of overcoming resistance.

I shall be endless. It can only die if every single rabbit is killed.

I shall occupy the world. The swarm can occupy another creature’s space and vice versa, and the swarm can move through any opening large enough for a Tiny rat. 

I shall live to eat. Eating gives this create stacks of Magic Ration. For every Tiny creature it eats it gains 1 stack. For every small, it gets 5. For every, medium it gets 10. For every large it gets 40. For every huge it gains 90. For every Gargantuas, it gains 160. 

I shall devour. It can fully consume someone whose hit points have reached 0.

I shall rain upon them. It can attack a number of times equal to the number of squares it is occupying while surrounding a creature.

I shall bite. Melee Weapon Attack: +10 to hit, reach 5 ft., 1 target. Hit: 20 (10d6 + 5) [Piercing] damage.

I shall be born anew. It can use it's bonus action to make more rabbits equal to the stacks it possess at the moment times.

I shall not fall. It can exchange it's stacks for hp. 1 stack equals 5 hp.

I shall have my revenge. If attack and receives any kind of damage, it can make a reaction attack to the attacker per square that is flanking the attacker.

I shall feed (Costs 1 Action). It can use it's legendary action to dismember a creature. The creature must make a dexterity saving throw. If failed the the creature loses an appendage or organ. The DC for this save is 16.