What Israphel Does
Israphel will only spawn when it naturally rains in your Yogbox world. If you try to hit him not long after he spawns, he won't take damage. If you go inside your house, Israphel will teleport into it with a golden sword. He can also hold a golden shovel at times. The rain will not stop until he explodes. He is not in the Yogbox files.
Israphel will try and circle you either to the left or the right, shooting an arrow at you every second. If you approach him, he will still circle you, but switch to a Golden Sword and try to move backwards. The best thing to do it to try and corner him, then move in front of his path and strike him with a sword. Upon his death, he will appear to sink into the ground. If damaged during the sinking phase, he will Creeper Hiss and violently explode, dropping a few Golden Apples and 1-3 blocks of Obsidian, and a very large amount of XP.
Early Fighting Strategy
(The Easiest Way to Defeat Israphel)
This is actually enough XP to level a player with no experience to level 25, so he is an excellent source of xp if you can manage to defeat. I would reccomend that a player wears at least leather armor and wields a stone sword. I managed to defeat him by camping behind a corner, in which I would hit him before he finished turning it, which knocked him back, he would walk up again, and I would hit him again. You sword will lose a lot of durability, but hell, it's stone! This is a great way to get your health up to 8 hearts if you manage to kill him early. NOTE: Due to the XP climb in leveling, he will NOT always give you 25 levels. If you are say, level 8, you will reach level 30. Level 12, level thirty one. Level 16, level 32....
MAKE SURE YOU USE A STONE SWORD!!! IF YOU USE WOOD, IT WILL BREAK BEFORE YOU KILL HIM. IF YOUR SWORD BREAKS, YOUR HAND WILL NOT HAVE ENOUGH KNOCKBACK OR DAMAGE, AND YOU ARE F*CKED.