OMG u gonna need alot of upgrades so forget it man !!!!!!!!! But i will tell anyway >>
First u need to give the tower upgrade abilities +5 +10 + 15 +20 so u create like 10000000 ugrades and when u finish a unit is killed by tower ext....... Research upgrade 1 ( +5 ) again a unit is killed by ..... Research upgrade 2 ( +10 ) it's very hard !!!
some wrong content
There are no Damage Tome by default (as I remember) but there is its ability which works like Manual of Health but increases damage instead of HP
should be something like Item Permanent Damage Bonus (I really dont remember)
Look I'll just sort everything up here in easy way
Attack Speed Bonus:
Modify Item Attack Speed bonus to minimum value you will use (like %10 for example)
Add it to a unit multiple times to get attack speed increased (if you add 1 times it has %10, 2 times %20 etc)