If you want the bot's health, use <var:ve:health>, for max health, <var:ve:maxHealth>, for bot damage, <var:ve:damage>
I've made an event contraption that gives a player a 100 HP shield., and if the player's is hurt, the shield comes in and heals them.
However, Bot Events lacks the right mixture of inputs and targets for this to work.
You can give a bot armor by adding a certain amount of health each time the bot is damaged, but that's about it.