To Make In a Burning House
I am the best thing to make if you’re in a burning house. And you’d better make me quickly before the fire’s too hot to take.
Haste. You need to make haste to get out of the burning house as soon as possible.
Slice My Head
You use a knife to slice my head and weep beside me when I’m dead.
An onion.
Grow In Trees and Have No Teeth
I grow in trees, eat living things but have no teeth and give birth to something that looks nothing like me. What am I?
A bird. They are hatched and raised in trees (nests), don’t have teeth in the traditional meaning of teeth and they lay eggs, which look nothing like a bird.
A butterfly / caterpillar could also work.
I Wear You Down
I wear you down, yet you will mourn me once I fly.
You can kill me, but I will never die.
Time.
(found in The Copper Gauntlet by Holly Black and Cassandra Clare)