a) Spurious Brontosaurus' first sighting of the Gaul's superstrength potion becomes Burke's first encounter with the facehugger
a.i) Spurius Brontosaurus leader of Pepe's Roman escort, in order to retrieve Pepe from the Gauls unseen, buys himself a cart and becomes a cart driver claiming to be a nomad.
By chance gives Asterix, Obelix and Pepe a ride when the cart of the previous person giving them a lift breaks an axel on a hole in the road.
On the journey, they are attacked by bandits but Spurius comes face to face with the sight of Asterix taking his magic potion to give him extra strength and the results of it.
He is overwhelmed with desire to get hold of it himself
b) Why the Face Hugger becomes should be compared to the Gaul's potion of strength
Like the Gaul's potion of strength, the facehugger appears to unleash something of great power too.
They have two alive and so quietly he hatches a plan to get someone else infected with a "chestburster" and bring them back to Earth inside the hosts.
It might seem that the idea of comparing the Facehugger to
the Gaul's potion of strength would come in the following Asterix book
which was "Asterix and the Roman Agent", where the agent who is a
character Tortuous Convolvulus who can make people believe his lies and start fights amongs themselves.
It gets to a point in the story where Tortuous declares that he himself is the magic potion
He manages to give a vase with swan decorations to the Gaul chieftain.
The illustration looks as if it served as a starting off point for Giger's cutaway egg images.
The swan's flying feathers become the fingers of the face hugger inside the egg form.
See: Alien: Cutaway of the Alien egg with face hugger inside by HR Giger references vase from "Asterix and the Roman Agent", (Originally published: 4 June 1970). written by Author René Goscinny, illustrated by Albert Uderzo.