Binlor Ironshield is the god of mining. He is found in a subdungeon with an ENDISWAL glyph. Once you mine a few walls, you reach some gold. Don't fall for it it, keep mining to reach his altar.
There are two main strategies with Binlor. You can either stay with him, which is only to be done if there are no other gods to convert off to, or the optimal strategy of using him as a piety farm. If you decide to stay with him, just keep using boons to pump magic resistance, the best boon being stone heart, and destroy walls to negate the level up penalties. Save some piety for the endgame. When you're fighting the boss, use stone skin before every hit. This is especially nice if you already have stone form as it will give you resists and might. If you are going to convert off, rack up 100 piety, take 5-10 stone hearts to kill monster resistances, and then rack back up 100 to convert in. Remember, if you are in a level without a lot of walls, don't use too many stone hearts as you might run out of walls to convert.
Binlor also has a strong synergy with attacks that cause knockback, such as if your character is a Half-Dragon or has a Bear Mace. With Stone Form and Stone Fist, every attack in which you can bash the target into a wall will give you Might, piety, and a large amount of knockback damage in addition to your normal attack damage, and the resistances you get from Binlor (or just from destroying walls with ENDISWAL) will help you survive any retaliation. If you take this approach, it's a good idea not to take too many boons from Binlor so that you have enough walls left for your knockback strategy.
If you plan on staying with Binlor, desecrating a Mystera altar is usually well worth the negatives. Since Binlor's only chance of punishing you is a -10 on level up, you effectively earn +55 piety on any desecration. Mystera's punishment is 15% resistances to all enemies, and you can nullify this with 3 uses of Stone Heart (while beefing up your magic resist by 9%). Just make sure you have enough walls to compensate, and that you're not already at a high enough level to waste the punishment invulnerability.
Binlor is an extremely safe deity to convert to in the endgame, if you would otherwise be dealing with an unmanageable amount of piety fines (e.g. a GG worshipper who has a large stock of potions). In this respect, he is second only to God: Earthmother Earthmother. Even if you have no way of generating more piety with him, he can be worth converting to at level 10 for a last-minute boon and a boss fight free of divine restrictions on your behaviour.
Binlor removes all your resistances when you desecrate his alter or otherwise anger him. For characters without resistances, this means Binlor can be angered or desecrated freely and he is incapable of actually punishing you. While there are a few cases of characters that can ignore a deity's punishment, this is the only one that actually comes up with any frequency in practice.