TIR in helm doesn't give +2 mana after kill
Solution 1:
According to Arreat Summit:
Traps function as golems and summons
Also, from this page:
"Points of Mana After Each Kill" (prefixes Triumphant, Victorious) provides a small amount of mana every time the player kills an enemy. Any type of damage inflicted by the player works, kills by minions do not.
So traps damage doesn't count as player's damage and effect doesn't work.