Original

Fundamental Force (600/900 points): Galactus can use Multiattack and can't be targeted by Exploit Weakness and Mind Control.

My Herald (600/900 points): As you reveal your force, you may also reveal another figure of 150 points or less to become your Herald. Then each opponent may choose a character on their force to offer up as Herald. You may then either accept an opponent's Herald, or choose your own revealed one. The chosen Herald is added to your force. Your chosen Herald possesses the Power Cosmic team ability, the Flight symbol, and modifies their combat values by +1. In addition, they can use a standard power as listed on the Herald dial. At the end of your turn, you may freely turn the Herald dial to any slot. (It can't be turned any other way.) When Galactus begins the 600 point dial, you may return your Herald to your starting area on click #1.

You Shall Not Harm My Master (600/900 points): Whenever Galactus takes damage, place a Revenge token on this card. At the beginning of your turn, remove all Revenge tokens and give your Herald that many actions as free actions this turn.

The Necessary "Evil" of This Universe (300 points): Galactus can use the Mystics team ability and can't be targeted by Exploit Weakness and Mind Control.

Errata

My Herald (600/900 points): As you reveal your force, you may also reveal another figure of 150 points or less to become your Herald. Then each opponent may choose a character on their force to offer up as Herald. You may then either accept an opponent's Herald, or choose your own revealed one. The chosen Herald is added to your force at the beginning or your first turn. Your chosen Herald possesses the Power Cosmic team ability, the symbol, and modifies their combat values by +1. In addition, they can use a standard power as listed on the Herald dial. At the end of your turn, you may freely turn the Herald dial to any slot. (It can't be turned any other way.) When Galactus begins the 600 point dial, you may return your Herald to your starting area on click #1.

See the Colossal Stamina and Great Size entries for more information.

See the Charactess with different dials entry for more information.

During a tournament, can I offer a different Herald each round? For instance, if I see my first round opponent has a Stealth heavy team, can I offer a character with the Superman TA and then, when my second round opponent has a lot of Mystics, offer a character with Pulse Wave?
No. You must offer the same character each round of the tournament as your choice for a Herald.

What happens to the Herald if Galactus is defeated?
The effects of My Herald end, so it will no longer possess the Power Cosmic TA, have its combat values modified by +1, etc. But since the character is now a part of your force, it won't just disappear; it remains on the map and you can keep using it like you would use any other character on your force.

If I can give my Herald more than one free action from You Shall Not Harm My Master, do I have to pick a different game effect to activate with each free action? Or can I just keep using Hypersonic Speed (or whatever)?
Normally, you can't activate the same effect more than once per turn with a free action. But, for You Shall Not Harm My Master, you may indeed activate the same effect multiple times if that is your wish.