Help a noob: One button to mash for all my needs

[Higglez]

You don't like using keybinds? set your skills from 1-5 then shift 1-5. If all you do is PvE then that's all you need.

[Canidomini]

Cast Sequence macro, that will jump back to the beginning once combat ends, you change targets, all spells have been cast or its been more than 8 seconds since a button push:

#showtooltip
/castsequence reset=8/target/combat Pyroblast, Fireball, Fireball, Fireball

This would be a horrible idea for a DK since you have rune and RP management, but to each his own.

Some macros that I have on my Orc DK are as follows:

#showtooltip
/cast Blood Fury(Racial)
/use 13
/use 14
/cast Raise Dead

#showtooltip Death Coil
/cast [modifier:shift,target=Pet] Death Coil
/cast [nomodifier] Death Coil

#showtooltip Unholy Frenzy
/cast [modifier:shift,target=Warrior'sName] Unholy Frenzy
/cast [nomodifier] Unholy Frenzy
/cast [nomodifier] Summon Gargoyle


#showtooltip Pillar of Frost
/cast Pillar of Frost
/cast Raise Dead

#showtooltip Scourge Strike
/cast [target=pettarget,harm,nodead][] Claw
/cast Scourge Strike

#showtooltip
/castsequence reset=8.5/combat Dark Command, Death Grip

They each suit their own purpose

[Bitlovin]

This means you're pretty much looking for an "I win button" macro. Sorry, as far as I'm aware there is no way to create a macro that would do what you are asking.

Well... not without using third party software.