Imperial is weird. In America even though 20yards makes sense, we would probably say 60feet in conversation. Yards is only used in football and math problems.
Think it’s supposed to be be earth type not thunder in this paragraph .
Merlin thought for a moment. He had not much to prepare. The Wizard Heart in his Awareness had not been fused with the Darkness-type and Thunder-type Wizards Hearts but simulating fusion in the Illusory World would take a very long time.