Can I use Maximal Effect to make multiple use of Temporal Portal?
The problem is that playing Temporal Portal counts as an action. Using it with Maximal Effect would mean multiple actions within one turn?
The answer is right in the rulebook. It is often wise to search in the electrical version first:
MK:LL rulebook, page 10 wrote:
If you play Maximal Effect with Temporal Portal, you cannot use its basic or stronger effect more than once, as it counts as your action and you can do only one action per turn.