Wait, the amount drained is based on the amount of mana the enemy wizard has.
So every drain you do, reduces how much the other drains are going to do. More you drain in one turn, the less effective the spell is.
Won't be a big difference, but it will add up especially on the higher skill levels.
For instance, the 600 level. First cast drains 756. That means the AI has (756-180)/0.03 = 19200 mana. The next cast 'only' drains 733. Next one then does 701. Next one 680. Next one 660. Last one 640.
Total drained is only 4170. Which is less than 4 skill gained (around 3.4 skill to be exact).
So you've spent an entire turn to gain skill that will take 176 turns to be profitable. The ai still has over 15000 mana, so you haven't done almost anything to bother the AI combat ability. If the AI has 600 skill, you can assume that the AI has a power income of at least 3000, plus 40% for cheating bonus is 4200. They'll spend 600 in Overland spells, so their net income is 3600. They'll have ~400 mana maintenance, reducing to 3200. So IF you do that every turn you've turned their net mana income to -970. It will take you 20 turns of doing this to reduce their mana to income, except the drains will continue getting weaker each turn, so it will be more like 30 turns. And they will have a gold income of at least 1000, so when they get too low they use alchemy to offset your attacks. So now that doubles how long it takes to reduce them to 0. Call it 60 turns. 5 years of casting nothing but drain power. And while you did NOTHING ELSE, they continued summoning and cursing and buffing just as much as always.
This is NOT an economic weapon.
So every drain you do, reduces how much the other drains are going to do. More you drain in one turn, the less effective the spell is.
Won't be a big difference, but it will add up especially on the higher skill levels.
For instance, the 600 level. First cast drains 756. That means the AI has (756-180)/0.03 = 19200 mana. The next cast 'only' drains 733. Next one then does 701. Next one 680. Next one 660. Last one 640.
Total drained is only 4170. Which is less than 4 skill gained (around 3.4 skill to be exact).
So you've spent an entire turn to gain skill that will take 176 turns to be profitable. The ai still has over 15000 mana, so you haven't done almost anything to bother the AI combat ability. If the AI has 600 skill, you can assume that the AI has a power income of at least 3000, plus 40% for cheating bonus is 4200. They'll spend 600 in Overland spells, so their net income is 3600. They'll have ~400 mana maintenance, reducing to 3200. So IF you do that every turn you've turned their net mana income to -970. It will take you 20 turns of doing this to reduce their mana to income, except the drains will continue getting weaker each turn, so it will be more like 30 turns. And they will have a gold income of at least 1000, so when they get too low they use alchemy to offset your attacks. So now that doubles how long it takes to reduce them to 0. Call it 60 turns. 5 years of casting nothing but drain power. And while you did NOTHING ELSE, they continued summoning and cursing and buffing just as much as always.
This is NOT an economic weapon.