One of the uses of Might is, as has been mentioned, to adopt more (Portfolios) for oneself and even Domains. Once a god reaches the required level, carries out the required actions and have the Might to spare, they can add a portfolio.
The following are the requirements in order to add a (Portfolio):
A god must have used at least 3 Might points in the specific (Portfolio) before they are eligible to adopt it as theirs. For instance, a Water (Oceans) god who wishes to incorporate (Rain) into their (Portfolio) must spend 3 Might points on (Rain) related actions before they 'unlock' (Rain) as a portfolio which they can add.
A god must spend another 3 Might points in order to incorporate the (Portfolio). So, the above god spent 3 Might points on (Rain) related actions, now they need to spend another 3 Might points to incorporate it, just as they spend Might to level up.
A god cannot incorporate a (Portfolio) which is not within their Domain. So, a Fire-type god cannot incorporate (Rain) as a (Portfolio).
Each (Portfolio) requires 1 Level to sustain it. For instance, a Level 1 god cannot sustain any more (Portfolios) than they have. At level 2 they can add a new (Portfolio). So, before being able to add a new portfolio, a god must reach level 2 and fulfill the above requirements, then they must reach level 3 to add another and have fulfilled the requirements and so on.

These are the rules regarding portfolios. Domains are as follows:

A god must have used at least 6 Might Points in the specific Domain before they are eligible to adopt it.
A god must spend another 6 Might in order to incorporate the Domain.
A god cannot incorporate a Domain which is a natural opposite to one of their existing Domains. For instance, a god with a Water Domain cannot then incorporate Fire. Earth cannot incorporate Wind, Light cannot incorporate Darkness and so on. If you are unsure whether a Domain is a natural opposite to one of yours, PM a GM or ask in the OOC.
Each Domain requires 7 Levels to sustain it. So once a god reaches level 7, they can only sustain 1 Domain, the one they already have. Once they reach Level 14, they can add another, and so on.