1st spell stacks up to 7times max level, cd is 3seconds and each individual stack lasts 15seconds. doesnt that mean it can stack up to 5times at most? "Hari Senbon, each individual stack, lasts for 15 seconds." seems like u didnt mean that every new apply of the debuff reset the duration of all stacks together.
about 3rd skill the passive, seems cool and the way it applies, extra -armor bonus for every creep that is killed for 3seconds is nice but for every hero seems too little, just like u increased the bonus of armor reduction for when a hero is killed u should increase the duration.
this hero's spells doesnt seem too powerfull so i'd boost ultimate's stun to ~1.5s