Compulsory Effects also known as manditory effects are effects that must resolve, and are not Optional. When two or more effects trigger at the same time, the Compulsory effects all go to the beginning of the Chain, and the Optional effects are put to the end of the Chain. Compulsory Effects are identified in cards by the word "must" or the phrase "this is not optional". Monsters with mandatory effects usually lack the phrase "you can" in the card text. You should be aware of when effects are compulsory or optional. Certain cards like "Caius the Shadow Monarch" and "Man-Eater Bug" may seem powerful, but they can unintentionally work against yourself when your opponent's field is clear.