The expansion only entered The UK last week so a bit late on the playing but have been spellbook planning some cool ideas. Some ive tried, others not yet.
The triple cost of arcane magic is a big nuisance: His access to channel increase, Dispel and Nullify is limited, but feel he has the best ranged support and armour cards available. he can build a powerful fortress to shoot from.
One aggressive opening is to rush into centre with double move first turn, droping either a War-Machine or the watchtower outpost in warlord's zone during final quick cast step (depending on opponent's opening and mage). If i chose the watchtower, I can summon and rouse the beasts a powerful Turn2 shot from the deadshot sniper for 5+ dice. Then fortress up the location with Wall of Pikes, Quicksand, Mangler Caltrops, Fortified Position and add more shots with Goblin Slingers and Ivarium Longbow.
5 Cards i recommend for the Warlord becides the obvious (outposts + boulders):
Ivarium Longbow - Take distance and shoot, make them come to you through traps
Goblin Builder - saves a mage action to build fortress cards allows more bow shots
Fortified Position - Armour +2 to all friendly in the zone, scary Amoured Grunt horde
Regrowth Belt - Blocks and Nullify are hard to fit, but regenerate plus lots of armour is easier
Charge (on Helm of Command) - adds distance to a Thorg Strike and removes Slow on Iron Golem
I have had some mana problems with the warlord, but sometimes found that going the horde path mid-game can build up mana for me into the late-game. 2 grunts (one from barracks one from mage) does not exceed my channeling, so can build up mana while creating problems for my opponent.