WARNING: The following contains spoilers for The Human Target #3, on sale now from DC Comics.
The Justice League has always had strong members, through all of its iterations. Among the most powerful members of all though is the Green Lantern. Though there are a number of Earth's heroes who have used the name and become a part of the Green Lantern Corps, each is a powerful force in the universe. Even Superman, with all of his immense strength and abilities, could have trouble going up against just one member of the Corps if they had a particularly strong will.
That makes what happened in The Human Target #3 (by Tom King, Greg Smallwood, and VC's Clayton Cowles) all the more shocking. As Christopher Chance investigated the members of the quirky Justice League International as suspects in his own murder, he upset one of its most powerful members. The Green Lantern Guy Gardener had a grudge against Chance for getting together with his longtime love interest Tora Olafsdotter, aka Ice. When Guy took things too far, Ice decided to put an end to it. Even the Human Target was surprised by how she managed to do it.
Tora came at the most powerful Green Lantern with her ice abilities. Though Guy put up a protective barrier, it was, shockingly, not strong enough to hold off her blistering blizzard. That would make Ice even stronger than this Green Lantern, and he isn't just any Green Lantern either.
Guy Gardner is considered by many to be the most powerful member of the Green Lantern Corps. A Lantern's ring is already acknowledged as one of the most powerful weapons in the universe but how strong it actually depends on the wearer and their willpower. Hal Jordan is legendary for the vast amount of willpower he has, which was strong enough to hold the entity of fear, Parallax, at bay inside him for years. As for Guy Gardner, his willpower is even stronger than Hal's. In fact, it's so strong that it overloads his ring. He can often be seen with energy sparking off of it, even when he's just wearing it.
This makes Guy Gardner one of the strongest Green Lanterns and means that his constructs should be incredibly hard to break. Additionally, a protective bubble like the one he used against Ice is an automatic response of the ring as much as it is a conscious choice by the user. Therefore, less concentration would be required to maintain this construct. Nevertheless, Ice's power was able to break through it, seemingly with ease.
There are a few reasons why this could be the case. The most likely answer would be that Guy's willpower faltered because of who he was facing. He and Tora have a long romantic history, which is why he was bothering Chance all throughout this issue, and that could cause him to let his guard down. Perhaps he didn't feel the need to give this construct his all, or maybe he didn't want to.
However, as mentioned before, the protective bubbles are as much the ring responding to threats as it is the wearer. These simple shields are designed to withstand virtually any cosmic threat and draw on the willpower of the ring's wearer. Even if Guy did let his guard down because of his feelings for Ice, it would take an incredible amount of strength to break, even for the likes of Superman.
This underrated Justice Leaguer is more powerful than anyone suspected. This is something the Human Target acknowledged when he saw this incredible display of power for himself. Though everyone believes that "Ice is nice" and wouldn't hurt anyone, her tragic history, and her hidden strength show just how dangerous she really truly is. As it turns out, dangerous enough to take down the strongest weapon in the universe.