Morphing unit using Bear/Crow Form

Is it possible to morph a unit by adding either morph abilities (bear/crow form) without having to issue the order to morph itself? I read that it is possible to do so by adding and removing Spellbook with the morph abilities, but I haven't been able to get the intended results. I need the morph ability to be hidden by the spellbook.

I don't want a Chaos morph as it's intended to be for a hero.

Chaos works with heroes, you just need to take some precautions. See the ability guide for more details.

It says that Chaos causes item bonuses to be added to the morphed unit's stats, which could be rather problematic.

What I want to achieve with my spell is to morph the hero into an exact copy of that hero except that it has a lower base attack time, attack all units in the targeted area, and morph the hero back to its original form.

Sounds similar to Demon Hunter's ultimate, could you not use that? If you want the spell to be togleable instead of timed, there might be an option for that in the gameplay constants, I know you can set it for some spells like Divine Shield, not sure about Metamorphosis though.

I got the spell to work simply just by adding the morph ability (Bear Form) and issuing an order to morph, but the ability icon appears for a split second just before the caster morphs, even though the morph has a transformation time of 0.00.

I also realised that I cannot get the caster to attack reliably, sometimes failing to attack before the next interval of orders being issued (every 0.14s). Is there a way to fix this?
With a 1000% attack speed bonus, the caster having a base attack time of 0.6s, should be able to attack every 0.12s.

Attack speed bonuses cap out at -80% and 400%.

I'm not actually sure you can make the ability work how you want it to, since attacks can be interrupted by spamming other orders. Why not just pause/disable the unit, order it to play the attack animation, deal the damage then unpause/disable?

I want the unit to be able to attack the targeted units normally i.e. having orb effects work, such as lifesteal/corruption/envenomed weapons etc.

Does this mean that the only way for the caster to attack normally is to slow down the intervals at which the orders are issued?

That, or trigger all your orb effects.