OK I am gonna try to tackle the math. This assumes that my opponents have 30 MR since that seems to be the most common number at the start.

The constants are MP reds as well as 10% MP from the offensive mastery tree. oh and dominion gives 5% MP from the crystal scar aura. The MP reds give 8.55 MP, while %s stack multiplicatively so I believe that 5% and 10% would result in 14.5% MP.

30 MR gives 23% damage reduction, it think. If that is correct:

Taking into account MP reds, masteries and the aura, you get 30 - 8.55 = 21.45 x (1 - .145) = 18.34 MR which is 15.5% damage reduction. So, I guess this would be the baseline.

Also, at level 3 my spells do 89, 97 and 78. The ratios are .65, .60, and .55 respectively.

Soooo, if I just added 20 SP boots (scenario 1), I would take 30 - 8.55 - 20 = 1.45 * (1 - .145) = 1.24% dmg reduction or pretty close to true damage. My spells would do 88, 96, and 77.

Scenario 2 is buying Boots of Speed and a Blasting Wand (40 AP). My opponents magic resist would be the baseline ie., 15.5%. However, my spells now do 115, 121, and 100. Applying the 15.5% magic resist, the numbers are 97, 102, and 84.5.

So it would seem from a straight up damage comparison, scenario 2 does more dmg/spell. Again, I understand that faster boots can help do dmg, health helps keep you alive, CDR, etc.but that isn't the point.

Let me know if I don't understand the way these things work. Thanks.

Assuming 30 MR and 8.5 in runes, the boots will be less then a 20% increase in damage. So, if your AP ratios are high enough so the blasting wand adds greater then 20% of damage to the base of your abilities (which is likely) then the AP will do more. Now this doesnt factor in Mastery or Rune AP, but the same logic applies. If 40 AP increases the abilities tooltip damage by greater then 20%, go for the AP item..

What about Haunting Guise? How does that affect the situation, you get AP, magic Pen and Health, covering all but the movespeed you'd need.

for the level 3 team fight at top, i think health and movement speed are pretty huge. for most mages, i do [amp tome + ruby crystal + boots1 + 3 health pots] for the team fight at top. this lets me start with almost the same benefit as p.ring + boots, but i get one extra health pot and can quickly upgrade into either a sweeper or haunting guise.

also, while it's usually okay to assume 30 magic resist in summoner's rift, you'll often see 50+ while playing on crystal scar. every game is either [sorc shoes + haunting guise] or [void staff + a different set of boots2 (usually ionion or merc's)].

Sometimes I just take my MPen runes get sorc boots and rush haunting guise on LB and thats like 49 magic pen and all my damage becomes true dmg except to tanks