Lone druid is probably one of the fastest hero pusher in this current meta but you have to hit your item timings.

Minute 10-15 you need to have phase boots and deso then start pushing towers. Rush your AC after that and then decide which items to get from there.

After you break mid tower, TP to enemy safe lane and break the tower immediately then walk towards their offlane while farming NC and lanes, then break that offlane tower as well. At this point you can ask your team to stick with you and let your carry farm. If that's not possible, then once you take mid tower and safelane tower ask your team to play around their jungle, completely invade their jungle until they're choked out of resources. With a deso at minute 10-15 almost no one can stop you if your team plays around you.

Lone druid is very tanky when he has his ult activated, so staying in enemy jungle is not as dangerous specially if you have 2 supports and your offlane behind you. Your role is to just be the bastion or front line of the team until your carry is ready to fight.

Most of the time no core in the game is ready to fight LD 15-20 mins in, so you can probably take tier 2 offlane and mid by then, and you'll probably have AC at this point so you're extremely tanky.

Minute 20-25 buy 5 wraith bands and go rosh. Make your carry (not you) take aegis, then high ground with bear. 25 mins is a power spike because wraith bands will give you +28 armor and 400 HP, combine that with your trueform and HP talent and you're basically immortal. At this point you should be establishing map dominance because no one can kill you, no physical damage carry can take lone druid 1v1 at 25 mins, except when they have magic bursts so be careful if they do.

When going high ground remember to have an extra bear on cooldown, let the bear tower push and make your carry and your main hero stay away (If you have a void, it's a good bait for chronosphere) The bear alone can deal so much damage to tier 3 towers with deso and AC that you dont need to help it push. Your team should stay behind and look for opportunities to initiate.

Remember to not waste your carry's aegis, let the bear tank the towers and only make your carry dive when you guys get an opening to fight (When tower breaks, they wont get any armor bonus and HP regen bonus so you can dive then)