The Goat is one of the less threatening monsters in the dungeon, and any character who specializes in melee damage can destroy them with great ease. They are commonly referred to as "murder bait" and it's often possible to attack and kill goats three or even four levels above yourself. This makes them one of the best sources of bonus XP that you can find in a dungeon.
The best approach to killing a goat is to use temporary buffs such as CYDSTEPP or ENDISWAL to withstand a few extra attacks. Due to their low HP, goats simply cannot survive repeated attacks without a chance to heal and will quickly fall to a well-prepared onslaught. Spellcasters may have a more difficult time due to the goat's magic resistance.
Because of their magic resistance, poison from the APHEELSIK glyph is unreliable. However, their resistance is not particularly high so poison still has fairly good probability of working. If you cannot kill a high-level goat by other means and you only need one or two more attacks to pull off the kill, then this can be a very worthwhile gamble.
The goat boss, Bleaty, has very high attack and low health. On some of the more difficult scenarios where monsters have boosted stats, Bleaty nearly reaches 300 points of damage. This makes survival even a single attack exceedingly difficult. In addition, Bleaty has 50% magic resistance, so BURNDAYRAZ is less effective against him - though it is still often the best way to deal with an unexpected Bleaty. To defeat this boss, you will need to prey on his low hit points or else find some way to survive his damage.
The best way to fight Bleaty is by worshipping Binlor Ironshield. Virtually all of Binlor's boons are valuable for your battle against Bleaty. Since he can grant you temporary 65% physical resists, a character with sufficient hit points can survive the goat quite easily. He can also reduce Bleaty's magic resist to leave him vulnerable to conventional spellcasting. His and boons both improve the potency of your physical attack, allowing you to finish the battle more quickly.
Other methods of surviving Bleaty include Death Protection, overheal effect from Life steal, or any form of Physical resist. Another method is to use the PISORF glyph, which deals physical damage and is unaffected by Bleaty's magic resistance.
BURNDAYRAZ is also a viable way to deal with Bleaty. He has 50% Magic Resist, but also his health is only 50% of what you'd expect a standard boss to have, so in effect you will need as many fireballs to kill him as you'd need for a generic boss. Even a character with no boost to spellcasting power can use a combination of mid-fight level-ups and mana potions to deal enough Fireball damage to Bleaty.