Looks very op.
I explored both kit names already in 2017/18.
Cactus Kit
To get a hit on the opponent every time they hit you, you would probably need a high thorns enchantment, but Thorns 5 on all pieces is not the way because 1.7 adds all thorns enchantments together, not like 1.8 where one piece gets randomly selected for thorns to activate, and will deal 5 hearts of damage on average. (armor is ignored)
And then comes to the addition of your overpowered sword, diamond sword, and strength is already strong for a kit that doesn't possess abilities, the more unreasonable it seems to me to add sharpness 1 and speed 1 to it.
To me, Cactus should be more of a passive kit, one that uses its strength of sending a bit of their pain back at the attacker.
For 1.7, my kit has Thorns 2 on Helmet, Leggings, and Boots, and Thorns 4 on Chestplate.
For 1.8+, it had Thorns 14 on every piece, a constant 2 hearts per hit damage because when Thorns exceed Level 10, the formula changes to `Level - 10` damage.
Turtle Kit
Deciding the look of the kit before me, is good, even though I had 2 years.
But just like Cactus, it seems similarly overpowered.
It's said on Munchy a Sharpness 3 Stone Sword equals a Sharpness 1 Diamond Sword.
So not only do they take 60% less damage from all sources after a hit (for an unknown duration), their only drawbacks are Blindness (which can be removed with fog-removing shaders) and Slowness 3.
Also, if they have Water Breathing, they don't need Respiration, if the enchantment is what you wanted since Aqua Affinity only makes you able to break blocks in water as if your head is not being covered by water.
Links
Cactus [1.7]
Turtle
For Vurm
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