Forums → The Tavern → Tabletop RPG Combat System That I Made, Need Revision

OK, so I'm making a tabletop Role Playing Game, and I wanted to sort of make my own combat system.
I have sort of a rough draft, and I need help revising it so it can become better and have less flaws. If you could help me that would be great.
How it works
This system is largly automatic, so players don't really get to control their every action in combat. However, they can set a sort of auto attack pattern so they can control their character to a certain degree. If they character takes a substantial amount of damage, then i do let them control whether they choose to flee, keep fighting, use a potion, ect.... I do this because if you die in this game setting, then you really can't come back, which might be strict or harsh, but it would make people make better decisions with their character and they would sort of 'bond' with it.
Anyways, players hit points (or hearts) are in the range of 2-4. 2, for the more frail classes (like wizard or rouge) and 4 for the more tanky classes like the Guardian.
At the start of the battle, players would roll a d20, or i would for them, and the enemy would roll this also a d20. This detirmines who goes first at the start of the battle (kind of like rolling initiative in D&D). If they get the same number, then monster goes first. (also kind of cruel on the players, but then again, most likely the monster will know their own territory you're invading) If it is Player vs Player Combat, then i just re-roll.
So lets say Bob the Builder is facing an evil creature, lets say the Keebler elf. Bob rolls a 14 for his initiative and Keebler rolls a 4. Bob goes first.
Bob's player attacks the Keebler elf. Bob's To-Hit-Bonus (or THB) is a +3 (that +3 comes from his weapon, lets say a rusty shovel). So he rolls another d20, lets say 10, and adds his +3 THB, along with any other bonus, and that would be his total Attack Value. In this case its 13.
The Keebler Elf does the same thing, and adds his To-Block-Bonus (TBB), usually coming from armor or potions. So lets say that Keebler gets like a 16. He would have blocked the attack, therefore ending Bob's turn and giving Keebler an attempt to strike now.
But let's say Bob got like an 18, so he beat Keebler's 16. He would deal one heart of damage to Keebler(or depending on the type of weapon he has he might do more). Normal low level creatures have one heart, so Keebler would be dead and Bob would loot the elf's cookies and sweets in his inventory.
On the roll of a 1 or 20, that is an automatic critical or failure. On a 20, you automatically block the attack or hit the target. On a one, well, you can probably guess that you automatically miss the target or don't block the attack. If both people get a 20, or if both people get a 1, then that is a stalemate and the round is over and its the next person's turn.

That should be all..... There is no leveling up in this system for different reasons, but you do keep track of your xp for questing purposes, like you might need an xp count for doing a certain quest or task.
You do't gain any xp for killing a foe or completing a task that is extreamly easy to you, that way farming low level people is reduced.
Ok, feedback is well wanted and if I didn't mention something clearly, comment and i will make it clearer.