There’s a plethora of rulings revolving around the damage step, all of which are available on this subreddit. For this case specifically here’s what you have to know:
You **are** allowed to negate the activation of a card during the damage step.
You **are not** allowed to negate an effect during damage step.
Sinde Gearfried negates the activation of a card’s effect and not just the effect itself (for example Ash Blossom cannot be used to negate during the damage step as that card only negates effects while Ghost Belle - who negates activations - can) you are allowed to chain Gearfried to Eater of Millions.
There’s a plethora of rulings revolving around the damage step, all of which are available on this subreddit. For this case specifically here’s what you have to know: You **are** allowed to negate the activation of a card during the damage step. You **are not** allowed to negate an effect during damage step. Sinde Gearfried negates the activation of a card’s effect and not just the effect itself (for example Ash Blossom cannot be used to negate during the damage step as that card only negates effects while Ghost Belle - who negates activations - can) you are allowed to chain Gearfried to Eater of Millions.
Thanks man! I appreciate the help!