There are 16 words that start with 'magis'.
| magister | magisters | 
| magistral | magistracy | 
| magistrate | magisterial | 
| magisterium | magistrally | 
| magistrates | magisteriums | 
| magistracies | magistrature | 
| magisterially | magistratical | 
| magistratures | magistratically | 
Note: These 16 words that start with 'magis' are found from the USA & Canada version of the tournament Scrabble word list.