So I just attempted to invade a barren planet that belonged to a lvl 104 in a legion of 24 people... The planet has 314 defense, 500 attack... There's no special artifacts on the planet that give bonuses (ie statue of magus etc.) I have 2600 attack +400 invasion bonus, 1100 defense, shitastic scan/cloak... yet when I lowered the pop and tried to invade it told me I only had a 14% chance to invade.. any ideas how that's even possible? I did do the standard 20 damage per hit to the planet and even upon invading there was no last minute defenses or guarding... Also I checked before and afterwards and I hadn't triggered any traps beforehand

That does seem odd, you're positive there was nothing on it that gave Invasion Defense?

Does seem strange that you only had a 14% chance, but how did you get +400 to invasion and 314 seems a rather odd number for defense. And as far as invasions go, the only number you need to have at the shitastic level is attack.