If don't have an interrupt or a stun, just don't even try to 1v1 a rook. When engaged on same level and skill, a rook will rely on pots, hammer and eventually try to TP out. And thats stuf you HAVE to counter. So for instance, if you play DA or QoT, just don't even try. Then you WILL need a Sigil of Vitality and/or a couple of Big HP pots.
Now let's take a second and look at the Rooks strong suits :
- Towers
- Boulder + Hammer
Towers: Boulder + Hammer A good rook player will Stack tons of HP and armor, so expect the fight to last. The best thing ofc would be to fight a rook before he raises his farm, but that's just common sense. So assuming you'll fight him in his towers, your best option is ARMOR. Try to get at 50% armor, and you'll be able to ignore them for a while.
Boulder + Hammer: Now he comes the tough part, especially for melee DG, escaping the hammer. After the boulder, spam your interrupt to have a chance to avoid the hammer, or spam mist if you're playing LE. At later levels, you will automatically take the hammer, cause the stun duration of the boulder roll is just too long. Use your pot right after the hammer, so the Rook cannot interrupt you while you drink it and save your stun/interrupt to prevent him from fleeing or healing.
That's about it, personally i think the best counters for Rook in 1v1 situation are Oak (shield + Penitence), Erebus (Bite + mist + Batswarm) and TB (Shatter, Ice Nova to freeze the towers, High dps).