Deckard Cain by Demolij

Cain is essentially a support with a lot of utility and cc that fits in with wombo-combo teams, or heroes that need assistance to be powerful. Identify is kind of a fun little minigame for your team to play: if they're pushing then occasionally an item will drop from minions (with that satisfying DIII drop sound) and your teammates will pick it up. Then they need to bring it to you when necessary and you can identify it, granting them a sizeable buff for quite a while. It forces them to pay attention to your well being otherwise they won't get their buffs, and enemies will obviously want to eliminate him to deny those buffs, making a really thematic VIP system for both teams. This is strengthened by his unique mount which lets him catch a ride on an ally, which is a good way to get around or tag along with a hero like Falstad, and can save you from an unfortunate fate due to the invulnerability.

Stay Awhile and Listen is kind of like Void Prison/Mosh Pit. You sit down, and as long as you're not interrupted you can sit there for a while. Then if enemies don't pay attention to you they will gradually all fall asleep, and since the ability lasts for ages your team will have time to catch up and trap them. It doesn't have a ton of range but if enemies get close they will quickly be slowed and knocked out. Using the ability when you're surrounded or under assault can easily stall your death or buy a ton of time for your team. It does have a lot of counterplay though, for instance if the enemy is out of range they can hit you with impunity, or if they're ballsy just waltz up and burst you within 1.5 seconds. If they fail though, they're gonna be in for a loooong nap. I also had an idea for how the sleep would look, and I think it would be hilarious if it just made the body ragdoll in place and flop to the floor.

Healing Potions are like little healing stations for allies that you can place nearby for them to pick up when they want to. The delay makes it hard to use them in-combat and they're easily denied by enemies but with good prediction they can provide a lot of nice heals. Trouble is a troublesome ability that can distract an incoming minion push from accomplishing things kind of like Sylvanas, and can possibly lead them on a wild goose chase to behind your towers. The active component makes you ultra tanky for a little while which is quite nice for not dying. It should be used whenever possible to ignore lane damage or high-damage abilities.

Horadric Cube is like a small healing Ward that can't be destroyed, and will grant your allies a large chunk of armor for quite a while. If your team is getting wombo'd this can potentially save them if you don't get bursted before you can use it, making it a pretty good ability if you intend on being closer to the action. Meanwhile the Book of Cain is a much more utility based passive that lets you apply a constantly stacking effect to a priority enemy by consistently stacking on them. It's special because it works separately from armor effects and only applies to each enemy written in. It's got a lot of range and can be nice for somewhat safely assisting your allies from afar though you still need to look out for assassins.