Encaustic is using a small hot iron to melt wax. You then used the iron to place it onto thick card and move it around until you have made a picture. I tend to draw patterns with it I like the arched shapes and feathered patterns you can make with the pointed end of an iron.
Other things you would need are newspaper to place the cards on while you are working with hot wax. Pointed heated styluses to draw into and with the wax, a fire blanket to place underneath everything. Cloth to clean the iron between different colour waxes and also soft cloth to burnish the final peice and bring out the shine of the wax.
Our set has about two dozen colours so there can be plenty of choices of wax to create different patterns.
I learnt to do this from one of the workshops our art group organises from time to time.