Regarding the Trainer (PATCH 06.29.2015), Reset Health, Reset Armor, No Pisto....
Found something peculiar with this new version of the trainer (Though it may be present in older versions). When fighting a "Boss" monster (That is, any monster that has a health bar displayed at the top of the screen, not the later "regular enemy" versions), if the trainer is active and the boss takes any damage from the player, the player will be teleported to the start of the level.
The only way to use the trainer for boss fights is to activate the "Reset Health/Armor" cheats, save the game before walking into the boss area,
exit the game (and close the trainer), then restart the game and tough it out through the fight. This is pretty much what you'll have to do with any regular enemies onscreen as well, as resetting your own health and armor also boosts any active enemy's health and armor.