Abilities with clear biological limits, like speed and strength, wouldn't scale as dramatically as elemental powers, and each level would only slightly raise the threshold. Theresa, as a peak-level ability user, had no equal at her level. However, compared to a Level 6 Strength-type zombie, she wasn't hundreds of times stronger. At most, five times stronger. After gauging the zombies' capabilities, Theresa was going to breathe a sigh of relief. However, she suddenly felt a monumental force surge toward her. Thud! A deafening roar shook the steel plate in front of her, as if a colossal war vehicle had smashed into it. The door she was holding with all her strength cracked open slightly, and a pile of zombie torsos and cores squeezed out like sugarcane water. This enormous force… "Damn it! There are six Level 6 Strength-type zombies!" Theresa's eyes widened in disbelief as both her hands strained to hold the door. From the tunnel behind, six Level 6 Strength-type zombies were charging in! She wondered what kind of cursed land could spawn so many high-level zombies? Rumble! Rumble! The steel plate in front of her shook violently. Each strike sent more zombie torsos flying. "How much longer are you going to take?" Theresa shouted. From behind, Kyle and the others yelled back. "The soil layer is different. We need at least another half hour!" "Speed up! I'll hold it!" Theresa gritted her teeth and continued holding the dangerously swaying steel plate. Under the full-force impact of the Level 6 zombies, the massive steel plate barely held. A cold glint flashed in Theresa's eyes. She decided to hold it for as long as possible. When she couldn't hold it any longer, she would fight. One minute… Five minutes… Ten minutes…Fifteen minutes… Slowly, sweat began to stream down Theresa's forehead. She was holding back opponents far beyond her strength. For the first time in a while, she felt her body burning with energy consumption, and her heartbeat was racing wildly. The thunderous impact echoed to everyone else in the tunnel. Harrance and the others heard the omnidirectional, bone-shaking crashes. It was like a mountain collapsing. Under such force, they felt as fragile as ants, ready to be crushed. Yet, they saw Theresa holding firm. Alone, she had withstood it for twenty minutes. In that split second, they wondered how strong she was. As they were awestruck, a sudden blaze lit up behind the steel plate. The temperature shot up instantly. A fire-ability zombie! And a very high-level one! It was a Level 6 Fire-type ability zombie! Flames shot out from the crack in the steel plate, scorching it red within seconds. At that moment, Harrance and the others thought it was over. After all, even a high-level fire-ability zombie had appeared. However, they saw a mist of water instantly extinguishing the flames and cooling the steel plate. The fire didn't flare up again. Seeing this, their jaws dropped as they realized that Theresa's ability level had to be higher than anyone outside! "No wonder they made her their leader…" Calvin muttered as he witnessed her power. Hearing his words, Harrance turned to him in disbelief. At that moment, Kyle's voice sounded, "Theresa, we dug through!" At the same time, the 30-centimeter-thick steel plate in front of Theresa tore open with a loud clang. A zombie's claw shot through the gap, aiming for her abdomen. Theresa's precognition ability reacted before the claw fully extended. She flung the steel plate aside and started to run. "Run!" As she spoke, the already-crowded tunnel behind her erupted, spewing a torrent of zombies. Six massive, strength-mutated zombies, far larger than the others, emerged like demons crawling out of hell. Their bodies were almost untouched, showing perfect form. They were clearly foreigners—pale skin, deep-set zombie eyes, grotesque faces. Strangely, they wore winter cotton caps and thick coats. Instead of looking like their country's military, they looked like they were resurrected from World War II.