Ally Limit
Each player is permitted to control a maximum of three allies in play at any given time. This is referred to as the “ally limit.”
A player may play or put into play allies beyond their ally limit. However, if a player ever controls a number of allies greater than their ally limit in play, they must immediately choose and discard from play ally cards they control until they have a number of allies in play equal to their ally limit. This occurs before abilities that resolve upon entering play.
See also