ability and buff questions

I'm a noob mapmaker with a couple of quick questions:

When you give a hero a passive ability, is there any way to make that ability do more than one thing? I can find trigger tutorials to make an activatable ability do more than one thing at once, but so far I can't find any that let you have two passive abilities for the price of one, ie. buying an ability that gives you an attribute bonus and a command aura.

How do you edit buff effects? I'm trying to make a cold spell with varying levels of slow as it levels up, but when I make custom buffs the map editor won't let me edit the values to change the slow %s.

A1) If the ability should stay in a item, then simply add multiple abilities in the appropiate item field.

A2) If the ability is for a hero, then you should use the spellbook trick:

• Find the Spellbook ability (it is under Special -> Items);
• Add your abilities in the "Data - Spell List" field;
• Edit the field "Maximum/Minimum Spells" according to your abilities;
• Now create a "dummy spell" for your hero (an ability which does absolutely nothing and works only as a place holder, for example a critical strike with 0% chance);
• Now create the following trigger:
  Trigger:

  Events

  Unit - A unit Learns a skill
  

  Conditions

  (Learned Hero Skill) Equal to Your Dummy Ability
  

  Actions

  Player - Disable Your Spellbook for (Owner of (Triggering unit))
  Unit - Add Your Spellbook to (Triggering unit)
  
• Disabling the spellbook will make the icon invisible, but the abilities will continue to work and the effect will be that your hero will have many abilities in one.

B) If you are looking for the "Slowed" buff (which is used for example in the Frost Nova ability) you can change its slow values only on the "Advanced -> Gameplay Constants".
Since you can't make multilevel slow % using Frost Nova or similar, you should base your ability on Drunken Haze setting the missile speed to 0 and changing its field (notice that you won't get the "blue effect" on the target).

I hope they were helpful :)

That was very helpful. Thanks!

It was actually much easier to just turn spell book into a hero ability. No triggers needed that way. :) Thanks for the idea though, I always wondered how maps made sub menus out of abilities, now I know! ^_^