Keltham will continue casting Guidance and using it to boost its own next cast until Haste runs out or catching fails, then practice more Read Magic without Guidance until another minute of that passes or catching Read Magic fails.

Keltham goes back to practicing at once.  He will continue casting Guidance and using it to boost its own next cast until Haste runs out or catching fails, then practice more Read Magic without Guidance until another minute of that passes or catching Read Magic fails.