It always bugged me that other AT's have the option to choose Villain epic pool pets meanwhile masterminds were excluded from this. I have several propositions to make ranging from modest to more extravagant.
At a bare minimum, I would like to suggest that villain epic pools afford MM's the opportunity to grab a boss/tier 3 epic pet. This would help increase their survivability and damage output. Considering MM's specialty are pets, I would take this one step further and remove, or increase the duration of the epic pet.
The more extravagant side of my proposition would entail several areas of improvement. Ideally, the elemental epic pools would provide a corresponding elemental pet(s) such as imps, snowmen, etc. Singular, or Plural.
To really push the idea, one could select a singular DPS, Support, or Tank Pet(s) from that particular epic, giving them flexibility to build for different activities. Or, they can call 1 of the 3 classes at a given time to help fulfill a need within the team structure.
Lets expand on this by discussing more on this topic.