Heroes of Might & Magic has been mentioned a few times erroneously. If we’re going to point at other games as examples, let’s get our facts straight. Just to clear things up…
This is incorrect–HoMM does not work that way. An archer in HoMM can move or shoot, not both. This is why you need to screen archers in HoMM with other units–because if an enemy closes with them, then they can’t shoot, and are forced to fight (very ineffectively) in melee, or flee. If they could move and then shoot, then they would be able to take a step away and then fire their bow. But that’s not how the game works.
It’s possible that Stridergg is confusing ranged units with melee. Melee units in HoMM can “charge”–take a move that ends with a melee attack. HoMM considers that to be one action. Which is good, because one action is all that any unit gets in HoMM, unless high morale grants them a free turn.
Or you will forego doing that because it’s not possible. Because it isn’t. Casters, like archers, can move or shoot, not both. In fact, IIRC, ranged units can’t even charge, like melee units can. You won’t even get the cursor, because if you mouse over a distant enemy, the cursor defaults to ranged attack. (Probably because nobody would ever want to charge into melee with a ranged unit, under any circumstances.) When you say “cast,” I think you might be thinking of the hero casting a spell, which is separate from unit actions (well, unless you are playing HoMM IV) and done from off the battlefield. That can be done at any time, and has no impact one way or the other on units taking actions on the battlefield.
Also, each unit has one action that they can do, not three. Well, they have multiple actions to choose from, but they can only do one of them per round.
In that case, there is a tactical choice of attack/attack/big spell vs. big spell/nothing/nothing.
This is not a tactical choice that HoMM ever offers you.