The masteries use different mana per tick based on your real skill level of Taming and Lore.
- 120 Taming, 120 Lore - Consume: 6/tick, As One: 12/tick
- 120 Taming, 115 Lore - Consume 8/tick, As One: 16/tick
- 110 Taming, 105 Lore - Consume: 10/tick, As One: 20/tick
So you can see, it can be quite a difference in the upkeep cost based on skill level, and it takes into account only your natural skill level for the purpose of mana upkeep.
So take the tick value, and apply LMC to it (hopefully 40%), this makes the ticks look like this:
- Consume: 3.6/tick, 4.8/tick, or 6/tick
- As One: 7.2/tick, 9.6/tick, or 12/tick
Ticks appear to be every 2 seconds. So your cost per second (CPS) is now:
- Consume: 1.8CPS, 2.4CPS, or 3CPS
- As One: 3.6CPS, 4.8CPS, or 6CPS
So based on that, you can calculate your Mana Per Second (MPS):
Mana Regeneration - UOGuide, the Ultima Online Encyclopedia
To Keep As One running indefinitely, you need 3.6MPS, which would be around 120 Med, 115 Focus, 150 Int, 30 MR. A very costly build (skill-wise), unless you happen to be a mystic tamer.
Permanent-Consume is a lot cheaper, needing only 1.8MPS, which can be done with only 30MR and 150 Int, if you are a human.
I always recommend getting more mana regen than is required, because if you need to cure, heal, invis, etc. you want to be able to slow regain mana. If you spec for only the exact amount of mana regen needed to permanently consume, you will eventually run out of mana with an occasional cast.