Searching for "Anti-Knockback" (Anti-KB) mods for Minecraft 1.8.9 usually leads to two different types of tools: gameplay-modifying items for survival and "hacked" client features for PvP. Types of "Anti-KB" for 1.8.9 Gameplay/Enchantment Mods : There are mods like the Anti Knockback Enchantment

Wait, the user mentioned "anti kb mod 189 top"—maybe "anti kb" refers to counteracting something else. Could it be a typo for "anti-KB" (keyboard) mod? Not sure. Alternatively, "kb" might stand for "keyboard" here. So "anti keyboard mod 189 top." Hmm. Maybe it's a specific term in forums or a specific mod that gained popularity as "189 top." Alternatively, "Topre switches" are known for their tactile and silent feel—maybe "Top 189" refers to Topre switches in a specific model.

If you meant something else by (e.g., a mod name, a server ID, a config value), please clarify and I’ll narrow the answer. Otherwise, the above covers the standard meaning of anti-knockback mods in Minecraft 1.8.9 PvP.