I included both of my go-to builds that I use for different situations. The Solo Heal build is specifically for games where I am the only healer so I focus primarily on keeping allies alive. The other build is exclusively for teams with another healer that allows me to play more aggressive support role with bloodlust. I have also experimented with subbing Healing Totem for Empowering Charge with teams that consist of heavy hitting attackers that can gain benefit from the attack buff. Both builds are subject to change but seem to be my favorite so far.

It's also worth noting that I am not the most established MOBA player. I've got my fair share of RTS experience with Master level Starcraft 2 play and I won't ever forget Brood War LAN's. Played a decent amount of Smite in my day as well but could never get in to League or DOTA. My experience team-based games is lacking so take my advice with a grain of salt.

I am almost never alone. Rehgar has very limited clearing abilities and about the only thing you can do is throw lightning shield on, position yourself in the middle of a pack and start clearing them one at a time. You're much better off assisting someone else that can do the clearing while you make their lives easier. With Earthbind Totem, you hold massive utility with an AoE snare. Combine this with the mobility of Ghost Wolf and the ability to toss out extra damage, and you become a nightmare for the enemy team.

Ghost wolf has no mana cost, usable in combat and is without a cast time. I would highly recommend getting the Feral Heart talent. Abuse this to maintain your mana while being mobile and cleaning up fires for your team, acquiring objectives, and securing kills with aggressive Earthbind + Lightning Shield plays. You have a fairly long cooldown on your abilities so its sometimes beneficial to get the most of your abilities and immediately hop in to Ghost Wolf to begin regenerating even while midfight. I try to get the most from the movement speed and try to secure vision points, grab coins, or secure merc camps while my abilities are on cooldown anyway.

Your main goal is to support, however. Chain heal is such a potent group heal and combined with Healing Totem, you pump out a lot of healing in group fights. Target the lowest health target first and cast as soon as you are able to efficiently heal multiple players. Chain Heal has a somewhat lengthy cooldown so you will want to start that asap. Healing totem has a 45 second cooldown and no mana cost so be sure to make the most out of this ability. It is amazing for team fights as well as allowing you to heal while being in ghost form to regen that oh so precious mana.

Rehgar can't help but shine with aggressive melee heroes so I tend to cover them more often. Everything else is fairly straightforward with Rehgar. The biggest part of your play that will change as you get better is being knowledgeable on where and when to be ready. Your heroic heal ability has a slight delay before it takes effect. There is also a very short range on earthbind, forcing you to be in the fray before placing the totem. Knowing exactly when and where to cast these two abilities can make or break team engagements. This is even more so the case with bloodlust. Obviously the timing comes with more experience so just keep at it and it'll get more natural.