theres 2 strats I use vs orc:
1. (the same as what Cool-T said) Archmage + Footies, militia creep a big spot right at the start, tech quickly and throw up 2 sanctums. Beastmaster 2nd hero, get a few sorcs and priests and hit them quickly, with Towers. (Ivory Towers from your shop, and bring 3-4 militia to repair)
If this push fails, expand, upgrade casters, and harass with beastmaster summons (invis bear) while creeping.. also get spellbreakers. Also make sure you put towers at your expansion.
2. MK + Footies, paladin 2nd hero, tech to mass griffons, and dont forget to expand. also get potions on both heroes (healing + invul)