Story time with Lax.
Source:
Marvel Heroes Terms of Service4.18 You may not create, post, use or distribute any utilities, emulators or other third party software tools (including, without limitation, macroing programs, botting programs, server emulators, client hacks, map hacks, and data gathering utilities).
Their Terms of Service explicitly states that you can't use anything at all, related to the game or not, while playing Marvel Heroes. You quite literally cannot play the game without violating this rule, because you require third party software tools in order to play the game (such as Windows and Direct X, these are not from you or Gazillion and therefore they are by definition third party software... and people can download and launch it through Steam, which is also a third party software tool!). The quoted stuff in parentheses is just fluff (examples), that's why it's in parentheses. Outside the parentheses, where it counts, this statement is missing a limitation on scope. Like, "relating to Marvel Heroes" or "that modifies the Game experience" and so on.
I put in a ticket with them regarding this about a month ago, including a question as to whether multiboxing would be allowed, and got absolutely no response to the ticket.
Because the terms are so broad, there is no way for us to determine whether multiboxing was intended to be allowed from a straight reading of the Terms of Service. After all, we can assume they want to allow FRAPS and other screen capture software -- which will operate within the game! -- as well as software like Mumble which has an in-game overlay. But their Terms of Service state that this is all prohibited (again, Windows and Direct X are also prohibited and there's no way to play without violating it).
Additionally,
the line of the Terms of Service is copied straight from Lord of the Rings Online's Code of Conduct, minus "without express written permission from Turbine", and it's even #18! But
Turbine has always allowed multiboxing, and indeed many people multibox LOTRO (and Turbine's other games including Asheron's Call 2 and Dungeons & Dragons Online) with ISBoxer. There's plenty of videos demonstrating it and nobody's been banned.
So, until they start banning anyone for multiboxing, or update their Terms of Service, or tell people not to multibox,
we have no indication that they want to prohibit multiboxing in Marvel Heroes and it's no more a violation of their Terms of Service than Windows, Direct X, FRAPS or Mumble.
I believe it is safe to multibox in Marvel Heroes.