One Tool

If you are on Creative, and want to level up your Techopaxel by cheating, there is a command :
/otexp : it give +500 000 exp to the Technopaxel in your hand

If you are on Admin, there is a config file that allow you to customize One Tool.

How gain Exp ?
-Break a block : +1
-Break ores : + depend of ore type
-Kill any mob : +100
-Kill a Witch : +200
-Kill a Iron Golem : +1000
-Kill a Amethyst Golem : +1500
-Kill a Wither : +5000
-Kill a Dragon : +10000
-Kill a Player : +20000

What about rare loots ?
-Witch can loot you one of the four enchanting books added by the mod (5% each only one loot possible), this loot is not a loot table modification, you need to kill with the Technopaxel.
-Amethyst Golem have a rare chance to give you a Base Boost Stone, this stone is easily craftable and the loot on the mob is since very rare.

Tips :

-I recommend that you make a wood farm to produce as much charcoal as possible at the early game. (with mods like bonsai pots 3 and chunkloading for example)
-By using autosmelt + lumberjack, cutting down trees allows you to refuel very quickly.
-Use your coal to refuel only when necessary! You can improve it with cursed amber.
-Make a mob farm for exp faster your Technopaxel.
-Try to have some villagers near where you live, to make it easier to get Heavy Books. (or make a witch farm)
-If  you're struggling to find an amethyst geode, you can try to find a lush cave because that's where the amethyst golems live