GingerBread4's Ice and Lightning Wizard Guide
Assigning Skill Points
30. Teleport (1)
31. Thunder Bolt (2), MP Eater (1)
32. Thunder Bolt (3)
33. Thunder Bolt (3)
34. Thunder Bolt (3)
35. Thunder Bolt (3)
36. Thunder Bolt (3)
37. Thunder Bolt (3)
38. Thunder Bolt (3)
39. Thunder Bolt (3)
40. Thunder Bolt (3)
41. Thunder Bolt (1), MP Eater (2)
42. Meditation (3)
43. Meditation (3)
44. Meditation (3)
45. Meditation (3)
46. Meditation (3)
47. Meditation (3)
48. Meditation (2), Cold Beam (1)
49. Cold Beam (3)
50. Cold Beam (3)
51. Cold Beam (3)
52. Cold Beam (3)
53. Cold Beam (3)
54. Cold Beam (3)
55. Cold Beam (3)
56. Cold Beam (3)
58. Cold Beam (2), Teleport (1)
59. Teleport (3)
60. Teleport (3)
61. Teleport (3)
62. Teleport (3)
63. Teleport (3)
64. Teleport (3)
65. MP Eater (3)
66. MP Eater (3)
67. MP Eater (3)
68. MP Eater (3)
69. MP Eater (3)
70. MP Eater (2), Slow (1)
Build Synopsis: 30 Thunder Bolt, 20 Meditation, 30 Cold Beam, 20 Teleport, 20 MP Eater, 1 Slow
Alternative Method: Instead of adding to Thunder Bolt first, add to Cold Beam, then add to Thunder Bolt When you normally would add to Cold Beam. You will level slower but save a lot of money.
Reasoning
The reason that I assign 1 point to MP Eater at level 31 is so that you get a boost, albeit a small one, for the next 10 or so levels so you don't have to use quite as many MP potions. Also the one point delay in thunder bolt means that at level 45 it is at 14 instead of 15, when the MP cost doubles. Adding to Meditation second also helps you to level faster and to use less MP.