Just on a side note... I have seen claims that the warlord is OP'd when combined with (some of the...???) essentials class... Though I'm not sure how accurate that is since no one in my group ever played a Warlord
By default, every 4e weapon class had a SCAG cantrip like booming blade or green flameblade. You hit for normal damage, and it had some extra effect like punishing someone if they move.
Warlords granted only basic attacks, not cantrips. So a generic granted attack was about 80% of the normal damage (which is why it also added +int). As you level, your attack becomes even less, so the warlord adds more.
Essentials classes where built around making a single good attack (like the 5e rogue). They got extra damage built right into the basic attack, so a warlord could do 110% damage with then. Stronger, but not OP.
The real way warlords became OP was because of how many different kinds of actions there where. You could grant 2 attacks with your action, then another with your bonus action, and another with your reaction, all with a big bonus to hit or damage. So you do 80% * 5 attacks = 400% damage, or 110%* 5 = 550% with an essentials class, all in 1 turn.
The highest I manged was to grant 10 attacks in 1 round (+4 if allies took the right feat). Not that I actually took any of my builds to a real game.
http://www.enworld.org/forum/showth...ar-Op-Builds&p=6707511&viewfull=1#post6707511
It would be like having twin haste, purple dragon knights action surge, commander's strike all together, with crusader's mantle and foresight tossed in for good measure, with the rogue doing full sneak attack damage each time. (...and now i need to see the maximum amount of attacks I can grant in 5e...)
5e's cut down on most of that by having only action, bonus action, and reaction (4e had action, bonus action, reaction, free action, opportunity action). As well as the 1/turn thing for rogues, and concentration.
It should be noted that most of 4e errata's where adding "once per turn" to things. Something 5e started with.