For a creature affected by Jeska's second ability, if that creature has trample, only the damage dealt to the defending player is tripled (as long as that player is one of your opponents). For example, say you activate that ability targeting a 5/5 creature with trample, attack one of your opponents with that creature, and that creature is blocked by a 3/3 creature. You could assign 3 damage to the blocking creature and 2 damage to the defending player. If you did, your attacker would deal 3 damage to the blocking creature and 6 damage (2 damage tripled) to the defending player. All of the damage remains combat damage.