He just out clears you early and is way faster at rotating than you. Oh and his poke is better.
Ra is a very basic god when you first look at him. His kit is very simple but he is definitely always my top pick for mid. His 1 Celestial Beam is a line attack that serves as your main way to clear and primary damage output. His 2 Divine Light is his escape, well your closest thing to an escape. The slow and damage are both decent but I primarily use his 2 as a damage output. His 3 Solar Blessing is what people primarily think of when they think of Ra. Use this to heal wave or your allies. You can out sustain most mid-laners because of this ability. Now the reason why Ra is my favorite mid-laner is because of his 4 Searing Pain. This ability seems like a lot of the other mage's ultimates, but the beauty of this ability is it's extremely low cooldown. At max rank the ability has a cooldown of only 50 seconds with no CDR. Now if this piques your interest read on, I will go in-depth about his match ups, his role in team fights and other things of that nature.
Before the game starts choose what you'd like to do, be it helping the jungler clear speed for extra XP, going straight to mid or being toxic and proxying from red buff. If you're an XP bot like you should be(come on you're in mid-lane)you'll start with the jungler at speed. If you do this correctly and get to lane before losing a creep you'll hit level 2 after the first wave. The goal when laning up until team fights start happening is to make your opponent wish he chose ADC instead. Your number one focus should be clearing wave, if you clear wave and have time between wave hit any of the harpy camps for extra XP. Prioritize Mid lane harpies for maximum hate on the foe in your lane, if you and your jungler properly clear mid-harpies and consistently have timer on them you're saving yourself from having to deal with an enemy mid-laner or jungler being ahead in XP. Sometimes when the event happens and your duo lane or solo lane are losing a fight a friendly Searing Pain can turn the tides but whatever you do don't go into lane to get this cheeky snipe all of your abilities except your 2 go through walls, so be a cheeky little mid and snipe them through the wall.Always ward no excuses.
Primarily in team fights you will be putting heaping amounts of damage on the enemy squishies, tanks aren't your target unless you're really fed. Don't give the enemy Osiris any more reason to stick to you. So basically don't allow the ADC, Mid or jungler to take objectives if you're there be a nuisance throw your abilities at them and get your team to clean up. If your team needs to top off on healing just throw your 3 down in a *safe* area, when taking objectives but your 3 in a place accessible for your team and yourself. Remember to throw your ult at your enemies your cooldowns should be super low with Chronos Pendant.
So here are the matchups real quick nothing too wild. If you're not favored it is because the enemy has CC and can keep you under tower.
Alright so that should cover Ra for the most part, this has been my first guide I don't know how well this is but I have been grinding ranked matches with Ra with success but take my words with a grain of salt I am no pro or anything like that. I started playing after AMA's drop and took a brief hiatus through season 4, this season I have been grinding and improving my plays with success. Thank you for reading please leave some constructive criticism and I will try my best to abide to your words.