my SoD knowledge is NOT perfect, but my understanding of the mechanic which was/is in game/live was that each mob negative interaction, be it a taunt, a spell cast on it, a DD, a melee hit, would give some aggro, which is why spamming a low damage nuke would give more aggro than doing a similar amount of damage with a single spell.As far as melee hits go, there's a set base amount of agro per swing, so the more swings the better. (IE: you'll generate more agro with a faster, weaker weapon than you would a slower, more powerful one).
Spells should be about the same.
On live spamming flame lick as a druid produced a ton of aggro. Don't know if it works the same here but if it does then it would stand to reason that yes a ton of 5 mana nukes is better than one big nuke. Keep in mind though that one nuke takes less time than casting a lot of small ones, so maybe it balances out in the end?
My 5m nuke only takes about 15% less time to cast than my biggest nuke and does about 10% of the damage. In an aggro race it would probably be way better to chain moon comet. Also moon comet can get ultimates and primals, while 5mana nukes cannot.
On live spamming flame lick as a druid produced a ton of aggro. Don't know if it works the same here