Yes,
Insult
will double all the damage from a creature with trample. However damage must be assigned from the unmodified amount first, and then doubled when dealt.
Let's say you're attacking with a 4/4 with trample, and you cast
Insult
during your first main phase.
If your opponent blocks with a 0/4 creature, when you assign combat damage you must assign all four to the blocker (assigning lethal) and there will be none leftover to assign to your opponent. Then damage will be doubled, dealing 8 to the blocker and 0 to your opponent.
However, if your opponent blocks with a 2/2, then you assign 2 damage to the blocker (lethal) and 2 to the opponent. When the damage is dealt it will be doubled, dealing 4 to the blocker and 4 to your opponent.
From the Gatherer rulings:
If a creature with trample you control would deal combat damage to a blocking creature this turn, you must assign its unmodified damage. For example, a 3/3 creature with trample blocked by a 2/2 creature can only have 1 damage assigned to the defending player. It will then deal 4 damage to the blocking creature and 2 to the defending player. (2017-04-18)
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Kogarashi says... Accepted answer #1
Yes, Insult will double all the damage from a creature with trample. However damage must be assigned from the unmodified amount first, and then doubled when dealt.
Let's say you're attacking with a 4/4 with trample, and you cast Insult during your first main phase.
If your opponent blocks with a 0/4 creature, when you assign combat damage you must assign all four to the blocker (assigning lethal) and there will be none leftover to assign to your opponent. Then damage will be doubled, dealing 8 to the blocker and 0 to your opponent.
However, if your opponent blocks with a 2/2, then you assign 2 damage to the blocker (lethal) and 2 to the opponent. When the damage is dealt it will be doubled, dealing 4 to the blocker and 4 to your opponent.
From the Gatherer rulings:
November 15, 2019 1:24 p.m.